Dissertations / Theses: 'FSCW'

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Oliveira, Pedro Henrique Freiria de. "Estudo das propriedades e desempenho mecânico de juntas soldadas por fricção pontual de poli (metacrilato de metila) (PMMA)." Universidade Federal de São Carlos, 2012. https://repositorio.ufscar.br/handle/ufscar/899.

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Universidade Federal de Minas Gerais
Polymeric components have been replacing traditional materials such as glass or metals in a wide range of applications due to their advantages, such as optimized specific strength (weight-to-strength ratio), reduced fabrication time and costs, and design flexibility. The increasing use of polymeric materials in engineering requires efficient and environmental friendly fabrication and processing technologies. Initially developed for metals, the Friction Stir Spot Welding (FSSW) is a joining technique with short process cycles, low energy consumption and no need of consumables. Friction Stir Spot Welding has excellent performance in welding of lightweight alloys, showing promising results in thermoplastic welding. This study investigates the relationships between friction stir spot welding parameters (tool rotational speed, plunge rate and dwell time) and weld properties (joint geometry, process temperature, microstructure, lap shear resistance and failure mechanisms) in polymethylmethacrylate (also known as PMMA) single-spot joints. PMMA friction stir spot welds showed similar mechanical performance in comparison to other current welding techniques, with equal or shorter welding cycle times. Differential scanning calorimetry and gel permeation chromatography analysis demonstrated that polymer degradation level in the weld region was negligible. The statistical models proposed for FSSW of PMMA showed good repeatability and reproducibility for the investigated material and welding ranges. Moreover, the feasibility of the Friction Spot Welding (FSpW) a new joining technology developed as a further improvement of the friction stir spot welding was successfully demonstrated in thermoplastic polymers for the first time worldwide. Sound FSpW-single lap joints on PMMA were produced and their properties studied within an exploratory study.
A busca por eficiência econômica e tecnologias ecologicamente corretas tem sido observada em praticamente todos os setores da produção industrial, desde o desenvolvimento de materiais, design de produtos e inclusive na área da soldagem. A soldagem ponto por fricção e mistura mecânica, FSSW (do inglês Friction Stir Spot Welding) e a Friction Spot Welding FSpW são técnicas de soldagem recentes e que têm sido amplamente empregadas na união de ligas metálicas leves, em que as soldas geralmente apresentam excelentes propriedades mecânicas. Além disso, ciclos de soldagem curtos, baixo consumo de energia e ausência de necessidade de adição de material ou elementos de soldagem são características positivas encontradas nesses novos processos. Na área de materiais poliméricos, entretanto, este é um novo e promissor assunto. Neste trabalho buscou-se investigar a relação entre os parâmetros do processo de soldagem por FSSW (velocidade de rotação da ferramenta, taxa de penetração e tempo de recalque) e as propriedades das juntas (geometria da solda, máxima temperatura processual, área afetada termicamente, resistência mecânica ao cisalhamento sob tensão e mecanismos de fratura) em placas de poli (metacrilato de metila). Foi possível observar a formação de juntas com resistência mecânica ao cisalhamento semelhante a outros processos atualmente utilizados na indústria, com tempos de ciclo de soldagem iguais ou inferiores a esses processos. As análises via calorimetria diferencial exploratória (DSC) e cromatografia por permeação em gel (GPC) demonstraram que os níveis de degradação termomecânica encontrados nas amostras foram insignificantes. A modelagem estatística do processo demonstrou a boa repetibilidade e reprodutibilidade dentro das condições estudadas. Nesse trabalho, também foi investigado através de um estudo exploratório, pela primeira vez, a viabilidade da nova técnica FSpW na soldagem de termoplásticos, demonstrando, com sucesso, a capacidade de obtenção de juntas de boa qualidade em PMMA.

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Gonçalves, Joel. "Soldagem pontual por fricção (FSpW) de poliamida 6." Universidade Federal de São Carlos, 2015. https://repositorio.ufscar.br/handle/ufscar/7314.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Friction Spot Welding (FSpW) is an innovative technique developed and patented in 2005 by the Helmholtz Zentrum Geesthacht (HZG) research center in Germany. FSpW uses the friction between a rotating tool and the workpieces to generate heat enough to cause diffusion across the interface to consolidate the weld. This new welding technology has been tested and optimized with the objective of produce overlap weld joints between two polyamide 6 plates. Full factorial design of experiments (24) and analysis of variance (ANOVA) allowed to explain the effects of weld parameters as rotational speed (RS), welding time (WT), plunge depth (PP), holding pressure time (HPT) and the interactions between these main parameters on the microstructural characteristics and mechanical strength of the joints. The rotational speed (RS) and welding time (WT), within the limits studied, had greater influence on the mechanical single lap shear strength of the joints that achieved up to 26 MPa. This behavior was related to the higher heat generation during the weld, reaching temperatures of up to 275°C, thereby increasing the welded area. The parameter holding pressure time (HPT), designed in this study allowed the cooling and solidification of the polymer under pressure, improving the weld surface finishing and avoiding defects as voids in the weld area. The most common failure for the joints with higher mechanical strength was the fracture of one of the plates while the joints with lower mechanical strength showed interface shear failure. The degree of crystallinity of PA6 in the welded area did not show a significant difference as compared to the base material. The molecular weight of PA6 in the welded area was reduced in the worst case 7% as compared to the base material (Mv = 41.800 g/mol), and that reduction occurred linearly with the increase of the temperature during the welding; however, that low degree of degradation was not found to affect the mechanical strength of the joints. These characteristics emphasize the potential of this FSpW as an alternative to the current welding methods for polyamide 6.
A Soldagem Pontual por Fricção (FSpW) foi desenvolvida e patenteada pela Helmholtz-Zentrum Geesthacht (HZG), na Alemanha. A FSpW é uma técnica de soldagem pontual que ocorre por meio da fricção de uma ferramenta, com movimentos rotacional e axial, através das amostras, gerando aquecimento suficiente para fundir e misturar localmente o(s) polímero(s), com posterior consolidação sob pressão. Este estudo teve como principal objetivo investigar o uso da FSpW na fabricação de juntas pontuais entre chapas de poliamida 6 (PA6) sobrepostas. Experimentos do tipo fatorial completo (24) e análise de variância (ANOVA) possibilitaram a compreensão dos efeitos dos parâmetros de soldagem, velocidade de rotação (VR), tempo de soldagem (TS), profundidade de penetração da ferramenta (PP), tempo de consolidação (TC), e de suas interações, sobre características microestruturais e a resistência mecânica das juntas. Os parâmetros velocidade de rotação (VR) e tempo de soldagem (TS), dentro dos limites estudados, apresentaram maior influência sobre a resistência mecânica das juntas, alcançando 26 MPa. Este comportamento foi relacionado à maior geração de calor durante a soldagem, atingindo temperaturas de até 275oC, consequentemente, aumentando a área soldada. A utilização do parâmetro tempo de consolidação (TC), idealizado neste estudo, possibilitou o resfriamento e solidificação do polímero sob pressão, melhorando o acabamento superficial da solda e evitando a formação de defeitos. Juntas com maiores valores de resistência ao cisalhamento sob tração apresentaram maior probabilidade de falha por fratura de uma das chapas, enquanto que juntas menos resistentes falharam por separação das chapas. O grau de cristalinidade da PA6 nas soldas não sofreu variação significativa e observou-se um decréscimo de até 7% na massa molar da PA6 em relação ao material de base (Mv = 41.800 g/mol) que ocorreu de forma linear com o aumento da temperatura durante a solda, porém essa alteração não comprometeu a resistência mecânica da solda.

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Kennard, Kirtis Frankland. "A Simple Method for Evaluating Wear in Different Grades of Tooling Applied to Friction Stir Spot Welding." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/5529.

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In this study tools consisting of a 5mm cylindrical pin and a 12mm shoulder held by a simple tool holder were used to compare the wear of 11 tooling materials. The objective was to determine if using these tools in a spot welding configuration to simulate friction stir welding could differentiate the potential performance of tooling materials. All tools were made of varying percentages of polycrystalline cubic boron nitride (PCBN), tungsten (W) and rhenium (Re). The materials are referred to herein as GV1, GV2, G1, G2, G3, G4, G5, G6, G7, G8 and G9.The tools were run to 205 welds if they did not fracture first. The grades averaged the following quantities of welds before fracture failure GV-1:0; GV-2:200; G1:82; G2:204; G3:205; G4:205; G5:96; G7:102.73; G8:21.2; G9:38.5. Of the tools that ran the full 205 welds without chipping, the average calculated volume loss, which was the best indication of wear, was as follows G2:1.83%; G3:2.53%; G4:2.41%; G5:1.93%; and G7:2.30%.The study showed that G2 had the least wear and G6 had the most wear, of those tools that completed all 205 spot welds. Fracture was the failure mode of all grades with over 70% CBN content. It was found that small CBN grain size was not correlated to better wear performance, as has been seen in a prior study.

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Ziegler, Daniel (Daniel M. ). "Compiling Gallina to go for the FSCQ file system." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113460.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2017.
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 85-87).
Over the last decade, systems software verification has become increasingly practical. Many verified systems have been written in the language of a proof assistant, proved correct, and then made runnable using code extraction. However, due to the rigidity of extraction and the overhead of the target languages, the resulting code's CPU performance can suffer, with limited opportunity for optimization. This thesis contributes CoqGo, a proof-producing compiler from Coq's Gallina language to Go. We created Go', a stylized semantics of Go which enforce linearity, and implemented proof-producing compilation tactics from Gallina to Go' plus a straightforward translation from Go' to Go. Applying a prototype of CoqGo, we compiled a system call in the FSCQ file system, with minimal changes to FSCQ's source code. Taking advantage of the increased control given by CoqGo, we implemented three optimizations, bringing the system call's CPU performance to 19% faster than the extracted version.
by Daniel Ziegler.
M. Eng.

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Matchett, Michael William. "Resolution of enantiomers using cyclodextrins in HPLC, FSCE and NMR." Thesis, University of Bath, 1996. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307070.

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Heinrich, Bernd. "Auswirkungen der FSC-Zertifizierung auf die Waldrestholzbereitstellung." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-202319.

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Ali, Khaled Yousif. "Friction Stir Welding Between Similar and Dissimilar Materials." Wright State University / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=wright1513857047779233.

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Karlsson, Alexandra. "Attityder till certifieringssystemen FSC och PEFC i skogsbranschen." Thesis, Linnéuniversitetet, Institutionen för biologi och miljö (BOM), 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-38481.

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Different groups in the forestry sector were likely to have different views regarding the responsibility for an environmentally sustainable forestry and the benefits of certification and this study aimed to examine the attitudes that existed in the forestry sector to the certification schemes FSC and PEFC. In the study a survey and a questionnaire were sent out to different groups. The investigation was made with respect to three groups: forest owners, forest contractors and employees working with the certification schemes on a daily basis at the forest company Södra. The groups agreed that the owner of the forest had the main responsibility for an environmentally sustainable forestry. The study revealed that all three groups highly valued the environmental aspect of certification. Forest owners also identified financial gain as a benefit. The forest contractors felt that the certification gave orderliness to their work but also saw an economic cost from being certified. The forest company employees found certification as an access to a widermarket with certified products. Half of the forest owners estimated their knowledge of the certification schemes to be inadequate while forest contractors and the employees of Södra valued their knowledge as sufficient. The forest owners had less education about the certification schemes than the other groups.
Olika grupper i skogsbranschen riskerar att ha olika syn när det gäller ansvaret för ett miljömässigt hållbart skogsbruk och nyttan med certifiering och den här studien gjordes för att undersöka vilka inställningar som fanns i skogsbranschen till certifieringssystemen FSC och PEFC. Arbetet gjordes med avseende på tre grupper: skogsägare, skogsentreprenörer och anställda som arbetar på skogsföretaget Södra med certifiering i sitt dagliga arbete. I studien skickades en enkät och ett frågeformulär ut. Undersökningen visade att de tre grupperna värderade miljömässigt hållbart skogsbruk med certifiering högt. Som skogsägare fick man en certifieringspremie för det certifierade virke som man sålde. Skogsägarna såg också en ekonomisk vinning med certifiering. Skogsentreprenörerna ansåg att certifiering i högre grad gav ordning och reda i deras arbete men att det fanns en ekonomisk kostnad med att vara certifierad. Skogsföretagsgruppen menade att certifierade produkter gav tillgång till en större marknad för skogsföretaget. Grupperna var överens om att ansvaret för ett miljömässigt hållbart skogsbruk låg på de/den som ägde skogsmarken. Samtidigt uppskattade hälften av skogsägarna att deras kunskaper om certifieringarna var otillräckliga medan skogsentreprenörerna och skogsföretagsgruppen ansåg att deras kunskaper var tillräckliga. Detta kunde bero på att skogsägarna fick mindre utbildning av certifiering än de andra två grupperna. Det här arbetet har visat att grupperna inte har olika syn när det gäller vikten av att ett miljömässigt hållbart skogsbruk bedrivs.

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Reese, Gregory A. "Dissimilar Friction Stir Welding Between Magnesium and Aluminum Alloys." Thesis, University of North Texas, 2016. https://digital.library.unt.edu/ark:/67531/metadc955097/.

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Joining two dissimilar metals, specifically Mg and Al alloys, using conventional welding techniques is extraordinarily challenging. Even when these alloys are able to be joined, the weld is littered with defects such as cracks, cavities, and wormholes. The focus of this project was to use friction stir welding to create a defect-free joint between Al 2139 and Mg WE43. The stir tool used in this project, made of H13 tool steel, is of fixed design. The design included an 11 mm scrolled and concave shoulder in addition to a 6 mm length pin comprised of two tapering, threaded re-entrant flutes that promoted and amplified material flow. Upon completion of this project an improved experimental setup process was created as well as successful welds between the two alloys. These successful joints, albeit containing defects, lead to the conclusion that the tool used in project was ill fit to join the Al and Mg alloy plates. This was primarily due to its conical shaped pin instead of the more traditional cylindrical shaped pins. As a result of this aggressive pin design, there was a lack of heat generation towards the bottom of the pin even at higher (800-1000 rpm) rotation speeds. This lack of heat generation prohibited the material from reaching plastic deformation thus preventing the needed material flow to form the defect free joint.

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Reilly, Aidan. "Modelling of friction stir spot welding." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/244946.

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Friction stir spot welding (FSSW) is a solid-state welding process which is especially useful for joining precipitation-hardened aluminium alloys that undergo adverse property changes during fusion welding. It also has potential as an effective method for solid-state joining of dissimilar alloys. In FSSW, heat generation and plastic flow are strongly linked, and the scale of the process in time and space is such that it is difficult to separate and control the influence of all the relevant input parameters. The use of modelling is well-established in the field of welding research, and this thesis presents an analysis of the thermal and mechanical aspects of FSSW, principally using the finite element (FE) technique. Firstly, a thermal FE model is shown, which is subsequently validated by reference to experimental temperature data in both aluminium-to-aluminium and aluminium-to-steel welds. Correlations between high-quality welds and temperature fields are established, and predictions are made for peak temperatures reached under novel welding conditions. Deformation and heating are strongly linked in FSSW, but existing modelling tools are poorly suited to modelling flow processes in the conditions extant in FSSW. This thesis discusses the development and optimisation of two novel techniques to overcome the limitations of current approaches. The first of these uses greatly simplified constitutive behaviour to convert the problem into one defined purely by kinematics. In doing so, the boundary conditions reduce to a small number of assumptions about the contact conditions between weld material and tool, and the model calculation time is very rapid. This model is used to investigate changes in the slip condition at the tool to workpiece interface without an explicit statement of the friction law. Marker experiments are presented which use dissimilar composition but similar strength alloys to visualise flow patterns. The layering behaviour and surface patterns observed in the model agree well with observations from these experiments. The second approach extends the FE method to include deformation behaviour without the need for a fully-coupled approach, guided by the kinematic model. This is achieved using an innovative sequential small-strain analysis method in which thermal and deformation analyses alternate, with each running at a very different timescale. This technique avoids the requirement to either remesh the model domain at high strains or to use an explicit integration scheme, both of which impose penalties in calculation time and model complexity. The method is used to relate the purely thermal analysis developed in the work on thermal modelling to welding parameters such as tool speed. The model enables predictions of the spatial and temporal evolution of heat generation to be made directly from the constitutive behaviour of the alloy and the assumed velocity profile at the tool-workpiece interface. Predictions of the resulting temperature history are matched to experimental data and novel conditions are simulated, and these predictions correlate accurately with experimental results. Hence, the model is used to predict welding outcomes for situations for which no experimental data exists, and process charts are produced to describe optimum welding parameters. The methods and results presented in this thesis have significant implications for modelling friction stir spot welding, from optimising process conditions, to integration with microstructural models (to predict softening in the heat-affected zone, or the formation of intermetallics at the interface in dissimilar welds). The technique developed for sequential small strain finite element analysis could also be investigated for use in other kinematically constrained solid-state friction joining processes.

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Makrickas, Evaldas. "FSC forest management certification analysis in Lithuaniua and Russia." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2011. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2011~D_20110601_115619-77809.

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First time name of certification were mentioned 1990s concerning a problems with bad forest practices, hard improvement of governmental regulations especial in tropics. Later this concern were growing to 1992 Rio de Janeiro conference. And so, need of strict forest system in 1993 established Forest Stewardship Council (FSC). Main activities started later 1996 in Canada with small group of people which started developing countries regional standards (Claros, 2009). Now FSC program is one of the biggest forest certification and accreditation providing company providing wood and their products and certification service. This program supports LEED Lumber, IKEA, biggest companies buying wood in the world, non governamental organisations World wild Fund (WWF), Green peace (www.fsc.org). The curiosity of how FSC forest certification impact forest management in Lithuania and Russia and lack of FSC standard studies with national law encouraged to create such study. We want to analyze FSC certification annual public reports raised CAR’s (Corrective action request) from Forest Management Units (FMU) - enterprises, leaseholders in Lithuania and Russia. The first aim was to find, what main CAR’s in Lithuania, Russia and distribute CAR’s to environmental, economical, social type aspects. In later stages analyze Lithuanian and Russian FSC standards Smart Wood, SGS Qualifor and Russian national. In the last step to compare FSC standards with state law for each country. Analysis of... [to full text]
Pagal FSC standartus miškai pradėti sertifikuoti nuo 1993 metų. Patogi sertifikavimo sistema leido minėtam standartui išplisti visame pasaulyje. Bolivijoje, Brazilijoje, Indonezijoje FSC sertifikavimas vis dar plečiamas (Claros, 2009). Sertifikacijos dėka gerinama miškų valdymo kokybė, biologinės įvairovės apsauga, sprendžiamos darbuotojų saugos problemos. Šio standarto visapusišku naudingumu neabejoja daugelis FSC rėmėjų: LEED Lumber, IKEA, bei didžiausios miško produktus superkančios ar nevyriausybinės organizacijos, Pasaulio gamtos fondas (World wild Fund WWF), Green peace (www.fsc.org). Mokslinių darbų, nagrinėjančių miškų sertifikaciją objektyviai, yra nedaug ir miškų sertifikavimo tema nėra plačiai nagrinėjama palyginus su socialiniais, miško gyvosios ir negyvosios gamtos sąveikos tyrimais. Miškų sertifikavimo standartų palyginamųjų darbų taip pat yra negausu. Šio darbo sukūrimo pagrindas – galimybė išanalizuoti skirtumus tarp FSC sertifikuotų kaimyninių šalių (Lietuvos ir Rusijos) miškų tvarkymo vienetų ir naudojimo standartų (MTV – Lietuvoje valstybinių miškų įmonių urėdijų ir Rusijoje miškų ūkių ir miškų nuomotojų). Taip pat norima sužinoti, ar Lietuvoje ir Rusijoje susiduriama su skirtingais sertifikavimo pažeidimais. Šių pažeidimų koregavimo veiksmų reikalavimų (KVR) aspektų pagalba palyginti Lietuvos ir Rusijos FSC miškų valdymo sertifikacijos standartus bei su standartais susijusi šalių miškų teisė. Kita šio darbo dalis, skirta ištirti kokią įtaką ekonominės... [toliau žr. visą tekstą]

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Souza, Henrique Cezar. "Projeto de dispositivo para ensaio de solda FSW sobreposta." Instituto Tecnológico de Aeronáutica, 2011. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2995.

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Desde que foi patenteado, no início da década de 90, o processo de união por FSW (Friction Stir Welding) vem despertando a atenção das grandes indústrias aeronáuticas devido às suas vantagens quando comparado aos processos convencionais de junta. No entanto, este é um processo que ainda depende de muito estudo e validação. O trabalho presente visa apresentar um dispositivo de fabricação e montagem simples que pode ajudar neste processo. Ele foi concebido para testar a resistência da solda do tipo sobreposta de reforçadores integrados a impactos, utilizando o conceito largamente conhecido do Ensaio de Charpy.

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Quercetti, Giovanni. "Analisi delle problematiche della FSW di leghe eleggere avanzate." Doctoral thesis, Università Politecnica delle Marche, 2014. http://hdl.handle.net/11566/242841.

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Oggetto del presente dottorato di ricerca è stato lo studio della saldabilità mediante il processo FSW delle leghe leggere d’alluminio e magnesio. In particolare, dopo una prima fase illustrativa della tecnologia FSW, si è intrapresa una sequenza di lavori sperimentali di seguito riassunti. Si è cominciato con la saldatura di giunti testa-testa analizzando tre argomenti principali, il primo dei quali studiava la saldabilità di un giunto dissimile tra una lega AZ31 e una AA6061 attraverso una caratterizzazione macro e microstrutturale. I risultati hanno evidenziato una saldatura priva di difetti con la zona del nugget caratterizzata da estesi fenomeni di ricristallizzazione in entrambe le leghe e fenomeni di interdiffusione sotto forma di precipitazione secondaria. Nel secondo lavoro si è ricercata la plasticità di giunti FWS dissimili alluminio-magnesio sottoposti alle alte temperature. Nel regime di alta sollecitazione, la deformazione del creep si è concentrata in questa parte del campione, mentre il metallo base AA6061 è rimasto indeformato. Nel regime di bassa sollecitazione, la deformazione si è avuta in modo più omogeneamente distribuito tra il materiale base AZ31 e la zona di mescolamento. La ricerca delle configurazioni d’estremità si è conclusa con una nuova tecnica di saldatura che prevedeva la doppia passata, ossia la saldatura da ambo i lati delle lamiere. Una comparazione dei giunti di lega AZ31 saldati da un lato con quelli da due lati ha evidenziato che nei giunti saldati con tecnica a doppia passata, si registra un aumento dei valori della durezza nella zona di mescolamento simili a quelli a singola passata e leggermente più elevati, ma si nota un miglior raccordo nella diminuzione dei valori fino ad arrivare nella zona inalterata del materiale base. Dalle prove di trazione si registra che i campioni saldati con doppia passata hanno avuto un incremento del carico di rottura (UTS) di circa il 9%. La ricerca ha avuto seguito con l’analisi della saldatura di giunti di sovrapposizione e con spessori. A tal proposito, si è cercato di valutare la saldabilità di una lega di Al AA5754 e spessori dissimili attraverso un piano di prove di saldatura. Si è fatta l’analisi della varianza per i tre fattori considerati come variabili e si è valutato l'effetto dei singoli fattori attribuendo loro una percentuale sull’importanza di controllo del processo stesso. I risultati ottenuti hanno manifestato una elevata variabilità, in particolare con la diminuzione della velocità di rotazione e con l'aumentare della velocità di traslazione.
The subject of this doctoral research was to study the weldability using the FSW process of light alloys of aluminum and magnesium. In particular, after a first phase illustrative of FSW technology is has undertaken a series of experimental work summarized below. It started with the welding of butt joints by analyzing three main topics, the first of which has studied the weldability of a joint between dissimilar alloy AZ31 and AA6061 through a macro and microstructural characterization. The results showed a welding without defects with the area of the nugget characterized by widespread phenomena of recrystallization in both alloys and phenomena of interdiffusion of aluminum in magnesium and magnesium in aluminum, in the form of secondary precipitation. In the second work was investigated the creep strength of a magnesium alloy AZ31 welded FSW. Following the creep tests performed , the observations of the curves showed that the beginning of the tertiary stage of the samples FSW occurs for lower values than the base material. The research for the butt joint configurations ended with a new welding technique which involved the double-pass, i.e. the weld on both sides of the sheets. A comparison of the AZ31 alloy welded joints on one side with those from two sides showed that the samples welded with technique from two sides, show a trend toward the elimination of discontinuities obtained with single pass, in addition, in the welded joints with technical double pass, there is an increase in the hardness values of the mixing zone similar to the single-pass and slightly higher, but there is a better fitting in the decrease of the valuesuntil arrive in the area of the unaffected base material. From tensile tests it was found that the samples welded with double-pass had an increase of tensile strength (UTS) of about 9%. The research has been followed with the analysis of welding of lap joints and with dissimilar thicknesses to vary the process parameters and the configuration of the tool. In this regard, we have tried to assess the weldability of an aluminum alloy AA5754 with dissimilar thicknesses. It has made the analysis of variance for the three factors considered as variables of the process and has assessed the effect of individual factors and give them a percentage on the importance of control of the process. The results obtained showed a high variability, in particular with the decrease of the rotation speed and with the increase of the translation speed.

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14

Ražauskaitė, Rita. "Lietuvos valstybinių miškų urėdijų sertifikavimo pagal FSC programą poveikio analizė." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120620_151755-00560.

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Šio darbo tikslas yra išanalizuoti pagrindines FSC standarto poveikio sritis. Tikslui pasiekti buvo apklausos Lietuvos valstybinės miškų urėdijos, kaip pagrindinis sertifikavimo objektas. Didesniam analizės patikimumui pasiekti buvo atlikta ir pilotinė girininkijų apklausa. Šių apklausų rezultatai buvo lyginami ir analizuojami. Norint giliau ištirti sertifikavimo poveikį išorinėms suinteresuotosioms grupėms buvo apklausti keturių numatytų grupių atstovai. Apklausų rezultatai susisteminti ir apibendrinti. Tyrimo metu nustatyta, jog sertifikavimas nepadarė žymaus poveikio miškų valdymui. Urėdijų ir girininkijų darbuotojai atsakymai buvo panašūs. Daugiausiai žymesnių teigiamų pokyčių buvo nustatyta socialinėje srityje. Aukščiausiai teigiamai įvertinti klausimai buvo susiję su lengvai pastebimais, išmatuojamais ir palyginamais pokyčiais. Sudėtingesni ir sunkiau pastebimi pokyčiai buvo įvertinti beveik neutraliai. Pvz.: “Valstybinių miškų rūšinė sudėtis”. Tai gali būti siejama su miško ekosistemų specifika. Ekonominių pokyčių vertinimo analizė atskleidė, jog po sertifikavimo urėdijos prekių kaina ir paklausa pakito labai nežymiai. Ekonominės paskatos yra pagrindinis sertifikavimą skatinantis veiksnys, tad galima teigti, jog Lietuvoje miško savininkai yra silpnai skatinami sertifikuoti savo valdas. Sertifikavimo poveikio skirtingoms suinteresuotosioms grupėms analizė parodė, jog reikšmingai skiriasi valstybinių ir privačių grupių atstovų nuomonės. Privačių organizacijų... [toliau žr. visą tekstą]
The aim of this paper is to analyze the main impacts of the FSC. In order to achieve this goal, the survey was the Lithuanian state forest enterprises as the main subject of the certification. For added reliability analysis was performed to achieve the rangers and the pilot survey. The survey results were compared and analyzed. To further investigate the impact of certification on external stakeholders were interviewed by the four groups. Structured interviews and summarized results. The study found that the certification had no significant effect on forest management. Enterprises and district staff responses were similar. The most significant positive changes were found in the social sphere. Extra points were assessed positively associated with easily discernible, measurable and comparable developments. The more complex and more difficult to assess changes were evaluated as almost neutral. For example. "State forest composition”. This can be attributed to the specifics of forest ecosystems. Economic impact analysis revealed that after certification of enterprises, and the price of goods and demand has changed very slightly. Economic incentives are a key factor leading to certification, so it can be stated that Lithuanian owners are not encouraged to certify their holdings. The certification effect analysis of different stakeholders showed the significant differences between public and private groups opinion. The Private organizations were less active and the means of... [to full text]

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15

Gratecap, François. "Études du procédé de soudage par frottement et malaxage (FSW)." Nantes, 2007. http://www.theses.fr/2007NANT2139.

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Le procédé de soudage par frottement et malaxage ou friction stir welding (FSW) est un procédé récent, mais compte déjà un grand nombre d'études théoriques et expérimentales. Toutefois, sur le plan scientifique, de nombreuses interrogations demeurent notamment la dynamique du malaxage, la formation des composés lors du soudage hétérogène, les champs thermiques induits et intrinsèques, le couplage champs thermiques-dynamique et structural. Par ailleurs, le choix des vitesses de soudages et de la géométrie de l'outil se fait la plupart du temps de manière empirique sans réel fondement théorique. Enfin, la courte durée de vie de l'outil demeure le verrou technologique majeur pour les alliages durs. Les principaux objectifs abordés dans cette thèse sont les suivant : L’étude de l'influence d'une perturbation de la cinématique de l'outil sur le mouvement de la matière. Tout d'abord, à une échelle macroscopique où nous étudions l'écoulement de la matière, puis à une échelle microscopique où nous étudions l'effet de la vibration de l'outil sur le malaxage de la matière. La mise au point d’une méthodologie basée sur un algorithme d'optimisation permettant de définir la géométrie d'un outil conique et les vitesses de soudage optimales pour un matériau donné. Cette méthode permet d’aboutir à une zone de soudabilité. L’étude de la problématique du FSW hybride assisté laser diode. La mise au point d’une méthodologie basée sur un algorithme d'optimisation permettant de définir la géométrie d'un outil conique et les vitesses de soudage optimales pour un matériau donné. Cette méthode permet d’aboutir à une zone de soudabilité. L’étude de la problématique du FSW hybride assisté laser diode
Friction stir welding is a relatively new process, but already has a large number of theoretical and experimental studies. However, at the scientific level, many questions remain including the mixing dynamics, the compounds formation in heterogeneous welding, induced and intrinsic thermal fields, coupling thermal dynamic structural fields. Moreover, the welding speeds and tool geometry choice takes mostly place in an empirical manner without real theoretical basis. Finally, the short tool life remains the major technological lock for hard alloys. It is in this research context that this thesis aimed at improving our understanding of the FSW process. The main objective of this work is to advance in the FSW physical phenomenon understanding and to develop a hybrid FSW assisted diode laser manipulation to start tests on hard alloys. The first point concerns the influence of a tool kinematics disruption on the material movement. First, at a macroscopic scale where we study the material flow and then at a microscopic scale where we study the effect of the tool vibration on the material mixing. The second point concerns the methodology development based on an optimization algorithm for defining the tool geometry and the optimal welding speeds for a given material. This method can result in a process window. The third point concerns the FSW hybrid assisted laser diode study. We present the thermal models used to define the laser parameters and discuss the first testing in steel and titanium alloys as well as for dissimilar aluminum-steel

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Gastebois, Sabrina. "Simulation numérique du soudage FSW à l'aide d'une formulation ALE." Thesis, Paris, ENMP, 2015. http://www.theses.fr/2015ENMP0040/document.

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Depuis l'invention du soudage par frottement malaxage (FSW) en 1991 par The Welding Institute (TWI), l'industrie aéronautique envisage de remplacer l'assemblage par rivetage des tôles par ce procédé. L'objectif est d'alléger les structures, plus particulièrement les panneaux des structures d'aéronefs qui sont souvent raidis avec des lisses et des profilés assemblés à la peau extérieure. La qualification du procédé FSW dans l'aéronautique requiert de produire des joints de très haute qualité avec une longue durée de vie des outils. Ceci nécessite un réglage fin des paramètres procédé tels que la géométrie de l'outil (dimensions de l'épaulement et du pion, filetage) et les vitesses d'avance et de rotation. Le but de ce travail est d'accompagner la conception du procédé par la simulation numérique. Il comporte trois parties: (1) le développement de la formulation arbitrairement lagrangienne ou eulérienne (ALE) dans la version parallèle du logiciel Forge® pour l'adapter au FSW, (2) la modélisation du procédé FSW et (3) la calibration du modèle EF et la validation des résultats numériques suite à la réalisation d'essais FSW en configuration par recouvrement.Ce travail est basé sur la formulation ALE parallèle développée dans Forge® afin de modéliser les différents défauts caractéristiques du FSW (bavures et trous). L'algorithme de transport des champs continus, indispensable au caractère eulérien, est affiné afin de considérer les particularités de l'écoulement du procédé (nœud du plan d'entrée, en contact avec l'outil ou dans les bavures et sortant du domaine d'étude). Un nouveau schéma d'intégration temporelle basée sur les coordonnées cylindriques plus adapté à ce procédé fortement rotationnel est introduit. Enfin, un filetage sur l'outil est modélisé par l'introduction d'une nouvelle loi de frottement à l'interface outil / matière.Cette formulation ALE générale et parallèle a montré sa robustesse pour modéliser le procédé FSW. Les résultats thermomécaniques sont en accord avec de précédents résultats validés par l'expérience. De plus l'outil numérique obtenu a montré ses capacités pour la modélisation des bavures ou des pertes de contact derrière le pion.Finalement la configuration de soudage par recouvrement industrielle a été étudiée. Pour cela des essais expérimentaux ont été réalisés pour divers paramètres du procédé et divers types de joints de recouvrement. Puis les mesures de forces et du couple dans l'outil et de la température dans l'outil et la tôle ont permis de calibrer les paramètres du modèle (frottement, loi de comportement, coefficients thermiques) et de valider les résultats EF
Since the invention of Friction Stir Welding (FSW) in 1991 by The Welding Institute (TWI), aeronautics industry has been investigating the possibility to use this process instead of riveting with the objective to lighten its structures and more particularly the aircrafts structure panels. Aircraft panels are often straightened with stringers and profiles which are joined to the outer skin. The qualification of FSW process in aeronautics requires producing very high quality joints with the longevity of tools, which requires fine tuning of process parameters such as the geometry of the welding tool (shoulder and pin dimensions, threads on pin and shoulder) and the advancing and rotating speeds. The aim of this work is to support the design of the process by numerical simulation. It has three parts: (1) developing an efficient and accurate Arbitrary Lagrangian or Eulerian (ALE) formulation within the parallel version of Forge® software, (2) modelling the FSW process and (3) calibrating the F.E. model and validating simulation results thanks to FSW experiments on lap joints.This work is based on the parallel ALE formulation developed in Forge® to model the different possible defects taking place in FSW (flashes and worm holes). The transport algorithm of continuous fields, required by the Eulerian frame, is enhanced to take the special characteristics of the FSW's flow into account (nodes located in input plan or flashes or in contact with the tool). A new time integration scheme based on cylindrical coordinates, which are best suited for this process, is introduced. Finally, the pin and shoulder threads are modelled by introducing a new friction law at the tool / material interface.This general and parallel ALE formulation is robust enough to model the FSW process. Thermomechanical results obtained are in agreement with previous results validated by experiences. And the numerical tool demonstrated its ability to model flashes formation and losses of contact behind the pin. Finally industrial welding lap joints configuration was studied. Experimental tests were conducted with several process parameters and type of lap joint. And measure of torque and forces in tool, and temperature in tool and sheet metal allowed to calibrate model parameters (friction, behavior law, thermal coefficients) and to validate FE results

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17

Schreiber, Rafael Gustavo. "Estampagem incremental e soldagem FSW para fabricação de coletor solar." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2018. http://hdl.handle.net/10183/183075.

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Este trabalho apresenta um modelo inovador de coletor solar plano, com placa absorvedora fabricada por Estampagem Incremental e Soldagem FSW (Friction Stir Welding). Esta placa absorvedora é constituída de duas chapas de alumínio AA1200-H14 com espessura de 1 mm, estampadas e soldadas em simetria, a fim de que na união das chapas sejam deixados canais para passagem de água. Neste estudo foi realizada a caracterização do material por Ensaio de Tração e Ensaio Nakajima. Para determinação dos parâmetros de Estampagem Incremental foram realizados 16 experimentos com ferramenta de diâmetro df = 9,5 mm, variando a rotação de N = 50 rpm a 800 rpm e o incremento vertical de Δz = 2 mm a 0,2 mm, mantendo o avanço em = 250 mm/min. E também foram realizados 3 experimentos com ferramenta df = 22 mm, variando o incremento vertical de Δz = 2 mm a 0,5 mm, mantendo a rotação em N = 50 rpm e o avanço em = 250 mm/min. Para determinação dos parâmetros de Soldagem FSW foram realizados 4 experimentos com ferramenta de ombro de diâmetro 8 mm e pino roscado M3x0,5, mantendo a rotação em N = 1500 rpm e variando o avanço entre = 100 mm/min a 400 mm/min. Em seguida foi fabricado um protótipo de placa absorvedora de coletor solar com área de 0,12 m². Nos experimentos realizados foi constatado que é possível obter maiores deformações na Estampagem Incremental do que na Estampagem Convencional e que as deformações são mais elevadas quando se utiliza menores diâmetros, maiores rotações e menores incrementos verticais da ferramenta. Na Soldagem FSW não foi constatada influência na qualidade do cordão de solda em relação à variação do avanço da ferramenta. Neste estudo também se verificou que é possível fabricar protótipos de placas absorvedoras de coletores solares pelos processos de Estampagem Incremental e Soldagem FSW. No entanto, para coletores em tamanho comercial, novos estudos são necessários para melhorar a forma de fixação das chapas durante a Soldagem FSW.
This work presents an innovative model of flat plate solar collector, with absorber plate manufactured using Incremental Sheet Forming (ISF) and Friction Stir Welding (FSW). This absorber plate consists of two AA1200-H14 aluminum sheets with a thickness of 1 mm, stamped and welded in symmetry, in order to leave channels for the passage of water. In this study the characterization of the material by Nakajima Test and Traction Test was performed. In order to determine the parameters of ISF, 16 experiments were performed with a tool of diameter df = 9.5 mm, varying the rotation speed of N = 50 rpm at 800 rpm and the step down of Δz = 2 mm to 0.2 mm, maintaining the feed rate at = 250 mm/min. Also, 3 experiments with tool df = 22 mm were performed, varying the step down of Δz = 2 mm to 0.5 mm, maintaining the rotation speed at N = 50 rpm and the feed rate at = 250 mm/min. For determination of FSW parameters, 4 experiments with 8 mm diameter shoulder tool and M3x0.5 pin were performed, maintaining the rotation speed at N = 1500 rpm and varying the feed rate from = 100 mm/min to 400 mm/min. A prototype solar collector absorber plate with a 0.12 m² area was then manufactured. In the experiments carried out, it was found that it is possible to obtain greater deformations in the ISF than in the Conventional Stamping and that the deformations are higher when using smaller diameters, higher rotations and smaller step downs of the tool. In FSW, no influence was observed in the quality of the weld bead in relation to the variation of the tool feed rate. In this study it was also verified that it is possible to manufacture prototypes of solar collector absorber plates by the processes of ISF and FSW. However, for commercial size collectors, further studies are needed to improve the way the plates are fixed during FSW.

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18

Huang, Dong Fang. "Investigation of Heterogeneity of FSW Inconel 718 Coupled with Welding Thermal Cycle." BYU ScholarsArchive, 2008. https://scholarsarchive.byu.edu/etd/1914.

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In order to develop a better understanding of the property, microstructure evolution and thermal history of FSW Inconel 718's, the strain, strain rate and thermal cycles need to be determined. In order to estimate the strain field of a deformed body, a displacement function needs to be determined. A 3D deformation model was developed to determine the displacement coefficients. A rectangular box created in this model deforms following a linear displacement function. Three orthogonal planes cut this deformed box, which leads to three deformed planes. The shape parameters (L, H, θ¹ and θ²) on the three orthogonal planes can be expressed as the functions of displacement coefficients. Although the displacement coefficients can not be expressed in the forms of the shape parameters symbolically, a numerical solution can be found using numerical optimization methods. The shape parameters were obtained by assuming the displacement coefficients (three cases). Then, the numerical optimization was carried out to determine the displacement coefficients. The solved displacement coefficients are the same as the assumed ones, which shows that this inverse problem can be solved, and this model is robust to determine the displacement function numerically. This model was used to estimate the strain and strain rate at the boundary of the nugget zone of Friction Stir Welding (FSW) Inconel 718. A numerical/experimental methodology was developed to estimate the thermal history in the stir zone of FSW Inconel 718.The thermocouple experiment was conducted to measure the thermal cycles in Heat Affected Zone (HAZ). Using the measured temperature in HAZ and a numerical model, the peak temperature (1039 ºC) and cooling rate (58.18 ºC/s) were determined. The microstructure in different regions was characterized and co-related with the thermal cycles. In order to understand the microstructure evolution in the stir zone, the strain rate (12.612 s-1) was estimated using the mathematical model as mentioned above. According to the estimated thermal history and strain rate, the assumption that the dynamic recrystallizaiton occurred during FSW was made. The grain size in the nugget zone affects the hardness. The relationship among the microstructure, mechanical properties, and thermal cycles was discussed.

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Dardouri, Fawzia. "Dispositif d’assistance associé à des robots manipulateurs utilisés dans des procédés de fabrication/FSW." Thesis, Paris, ENSAM, 2018. http://www.theses.fr/2018ENAM0036/document.

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Les robots industriels sont très utilisés aujourd’hui dans de nombreuses applications industrielles pour leur polyvalence et leur facilité programmation. Cependant, malgré leurs performances, ces robots ne sont pas adaptés à certains procédés de fabrication où des forces uniformes et élevées ainsi qu'une précision de positionnement appropriée sont requises. Le présent travail est axé sur la robotisation de l'une des opérations à forte charge, le soudage par friction-malaxage (FSW). Cette méthode d’assemblage s’utilise pour assembler des pièces en phase solide. Pour cette raison, une force de poussée très élevée est nécessaire pour ramollir le matériau pendant cette opération. En raison des forces élevées, la position de l'outil dévie de la trajectoire désirée. Dans ces travaux de thèse, la possibilité d'utiliser un dispositif d’assistance associé à un robot manipulateur est étudiée afin d’améliorer sa capacité de charge et sa rigidité. Dans une première partie, une modélisation géométrique, cinématique et dynamique ainsi que de déformation d’un robot industriel Kuka KR500-2MT est développée en localisant la flexibilité au niveau des articulations. La deuxième partie consiste à améliorer les performances de la robotisation du procédé FSW par différentes méthodes qui sont la modification du système de compensation de gravité, l’ajout d’une masse additionnelle sur l’outil, l’ajout d’une structure parallèle et l’utilisation de deux robots en mode coopératif. Les deux dernières solutions consistent à exercer des forces directement sur l’outillage. De cette façon, le mouvement de l'outil est principalement piloté par le robot industriel, tandis que le dispositif d’assistance (soit la structure parallèle ou le deuxième robot utilisé dans le système coopératif) assure la génération de forces de poussées très élevées. Des algorithmes d’optimisation ont été utilisés afin de minimiser les déviations de l’outil et donc réduire les défauts de soudage. Finalement, une étude de l’espace de travail est menée en utilisant le logiciel Catia. La connaissance de l'espace de travail pour les solutions proposées nous permet d’estimer les applications de soudage possibles ainsi que leur comparaison
Nowadays industrial robots are used in many manufacturing applications because of their versatility and easy applicability. Notwithstanding their performance these robots are not suitable for some manufacturing processes where uniform and high forces together with suitable precision of position are required. The present research is focused on the robotization of one of the high-thrust operations, the friction stir welding (FSW). This method for connecting two parts works while the connected materials are in the solid phase. For this reason a very high axial force is needed to soften the material during the welding process. Due to these high forces the position of the tool of a serial robot deviates from the desired trajectory. In this PhD work, the possibility of using a parallel structure device is investigated to improve the load capacity and stiffness of a heavy loadmanipulator robot. In a first part, the geometric, kinematic and dynamic modeling and the flexibility of an industrial robot, Kuka KR500-2MT are developed by locating flexibility at the joints. The second part is to improve the performance of the FSW process using an industrial robot. So different methods are examined: the modification of the gravity compensation system, the addition of an additional mass on the tool, the addition of a parallel structure and the use of a cooperative system. The last two solutions exert forces directly on the process tool. In this way the movement of the tool is mainly generated by the industrial serial robot, while the assistive device (either the parallel structure or the second robot used in the cooperatif system) ensures the generation of very high axial forces. Optimization algorithms are developed to minimize deviations and thus reduce welding defects. Finally, a study of the workspace is studied using Catia software. Knowledge of the system workspace with the proposed solutions allows to estimate the possible welding applications that can be achieved using these systems

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20

Miyazaki, Marcos Hideki. "Desenvolvimento de novo conceito de junção de reforçadores aeronáuticos por FSW." Instituto Tecnológico de Aeronáutica, 2009. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=1278.

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Este trabalho tem como objetivo estudar a viabilidade de se utilizar um novo conceito de soldagem entre perfis reforçadores de liga de alumínio da série 7XXX e chapas de liga de alumínio da série 2XXX pela tecnologia de soldagem FSW (Friction Stir Welding). Com este novo conceito, um perfil reforçador com geometria especial é soldado por FSW a uma chapa com o intuito de se fechar toda a interface entre a flange do reforçador e a chapa, esperando-se que se obtenha um ganho tanto em processo como em peso, já que o processo de fabricação se torna mais enxuto. O processo FSW foi inventado e patenteado pela TWI, um renomado centro especializado em junção de materiais, em 1991, no Reino Unido. Esta técnica de soldagem caracteriza-se por ocorrer no estado sólido, isto é, sem que haja a fusão do material a ser unido. No processo de soldagem FSW, uma ferramenta especial composta por um ombro e um pino é rotacionada de forma a gerar atrito entre as partes a serem soldadas. O atrito gerado pela ferramenta causa o aquecimento do material a ser soldado, que faz com que o mesmo seja plastificado, enquanto uma força axial aplicada pelo ombro da ferramenta consolida a solda. Duas ferramentas similares compostas por um mesmo pino, porém com ombros diferentes foram utilizadas para o desenvolvimento deste trabalho. Baseando-se nos parâmetros de referência da solda FSW sobreposta convencional, foram realizadas várias soldas pela metodologia de tentativa e erro. Em todos os casos, foi realizada análise visual das soldas FSW. As soldas que apresentaram boa qualidade superficial foram submetidas ao ensaio metalográfico, e caso não apresentassem nenhum defeito, seriam submetidos ao ensaio de tração transversal à solda, a fim de comparar as propriedades mecânicas entre a solda FSW sobreposta com este novo conceito e a solda FSW sobreposta convencional.

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21

Brumbaugh, David. "DISC, FSC, and the cost of capital in the export sector." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74513.

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DISC and FSC are two trade policy instruments of the United States that proV'ide a tax incentive for exporting. The two measures provide a stimulus for investment in the export sector by reduci.ng the cost of capital for exporting firms. According to a model based on the neoclassical theory of optimum capital accumulation, the minimum effect either DISC or FSC can have is surprisingly small, reducing the cost of capital by less than percent in either case. The maximum effect is large, reducing the cost of capital in the export sector by around 20 percent. However, the maximum effect of DISC and FSC is accompanied by side-effects that reduce economic efficiency significantly. These results therefore call into question the effectiveness of DISC and FSC as instruments of trade policy.
Master of Arts

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Rosendo, Tonilson de Souza. "Estudo do desempenho mecânico de solda(s) ponto por fricção (FSpW) da liga AA6181-T4." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/18981.

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Uma nova tecnologia de soldagem, denominada Friction Spot Welding (FSpW) utiliza uma ferramenta rotativa especial que transfere energia térmica e mecânica ao material sendo soldado. O processo se destina à soldagem de juntas sobrepostas, primariamente para ligas leves, mas, em teoria, é aplicável a qualquer material que apresente boa plasticidade. A crescente competitividade tem motivado as indústrias à otimização de processos, o que tem levado ao uso cada vez mais expressivo de ligas leves nas indústrias automobilística e aeronáutica. Soma-se a isto a necessidade de redução do consumo de combustível em veículos, dada a crescente preocupação com as questões do meio ambiente. Estes fatores tornam o processo FSpW um grande atrativo seja na substituição ou no uso complementar de tecnologias consagradas como soldagem a ponto por resistência elétrica e a LASER (indústria automobilística) e rebitagem (indústria aeronáutica). Neste trabalho foi feito um estudo da aplicabilidade do processo FSpW para a liga de alumínio 6181-T4 que tem forte apelo na indústria automotiva. O estudo teve como objetivo avaliar os efeitos dos parâmetros de processo, na microestrutura, na geometria da junta e no desempenho mecânico, além de buscar a otimização do processo para a liga em estudo. Tal otimização foi feita por meio do estudo dos mecanismos de fratura das soldas sob solicitação monotônica de cisalhamento e de tração. Juntas sobrepostas foram produzidas utilizando condições de soldagem variadas, por meio de diferentes combinações de velocidade de rotação e tempo de processamento. Os resultados obtidos mostraram que soldas de alta resistência e de reprodutibilidade são possíveis com este novo processo. O botão de solda FSpW da liga 6181-T4 é constituído de três elementos (União Principal, União Secundária e Cunha). As características destes elementos, somada às transformações metalúrgicas decorrentes do processo, afetam fortemente o comportamento em fratura das juntas e, conseqüentemente, o seu desempenho mecânico.
A new welding technique referred to as Friction Spot Welding (FSpW) suitable to produce overlap joints uses a spindle to transfer mechanical and thermal energy to the material being welded. Although initially developed for lightweight alloys this welding technique is suitable to virtually any material presenting some degree of plasticity. The process has shown potential applicability to complementary use together with other well established techniques such as resistance and LASER spot welding and riveting. In this work a study of the application of the FSpW process for the automotive aluminium alloy 6181-T4 was performed. Overlap joints were produced with different welding conditions by using different combinations of tool rotation speed and welding time. The objectives were the assessment of the welding parameters on the strength, microstructure and geometry of the joints, as well as the optimization of the process. The welded joints were assessed mechanically and metallurgically aiming the investigation of the mechanisms of joint formation and the optimization of the welding parameters. The methodology used for the optimization of the welding parameters was the fracture mechanisms of the joints under shear and tension loads. The results revealed that sound welds with high strength and toughness are possible to be produced with the 6181-T4 alloy using this process. Moreover, the metallurgical investigation revealed that the spot joint is comprised by three elements: Primary Union, Secondary Union and Rim. It was found that the characteristics of these three elements in addition to the metallurgical transformations imposed to the material play a fundamental role on the fracture behaviour of the joints and thus, on its mechanical behaviour.

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Atcherley, Christopher Wade. "Voltammetric Measurements Of Tonic And Phasic Neurotransmission." Diss., The University of Arizona, 2014. http://hdl.handle.net/10150/338965.

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To understand how the brain functions and what disruptions underlie neurological diseases and disorders, analytical methods are needed that can succeed in the complexity of the native brain environment. To make a measurement in functioning, live tissue, these methods must be selective for specific analytes in a matrix that has over 1000 different chemical species, be able to measure chemical changes on multiple timescales (10-3 s to 104 s), have a high spatial resolution (μm), and be sensitive (pM to μM). The work described within, details the development and application of a voltammetric method, fast-scan controlled adsorption voltammetry (FSCAV) that is capable of monitoring baseline levels of serotonin and dopamine, as well as monitoring changes on multiple time scales with high sensitivity and selectivity. Because FSCAV is performed using a carbon-fiber microelectrode, the same sensor can be used for fast-scan cyclic voltammetry to monitor rapid (phasic) changes of dopamine and serotonin in the extracellular space. Thus a single-sensor strategy for measuring tonic and phasic concentrations of these important neurotransmitters is developed and used to elucidate important insight into the differences of serotonin and dopamine regulation. Additionally it is revealed that dopamine exhibits a coaction between tonic and phasic signaling where serotonin does not. Using this approach, a method for evaluating pain processing in a preclinical model is developed, which reveals an important relationship between chronic pain and dopamine signaling. Furthermore, a mathematical model to describe mass-transport limited adsorption is developed and used to determine the diffusion coefficient of both dopamine and serotonin in situ. The work described within details an important advancement in neuroanalytical methodology that will provide new insights both short-term and long-term for studying fundamental chemical mechanisms of neurotransmission.

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Plaine, Athos Henrique. "Soldagem por fricção e mistura (FSW) no aço inoxidável austenítico AISI 304." Universidade Federal de São Carlos, 2013. https://repositorio.ufscar.br/handle/ufscar/900.

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Made available in DSpace on 2016-06-02T19:12:29Z (GMT). No. of bitstreams: 1 5325.pdf: 3683699 bytes, checksum: 93e192da88e53194c931c77433e3db00 (MD5) Previous issue date: 2013-04-09
Financiadora de Estudos e Projetos
Stainless steels are an important class of engineering materials with attractive properties such as high mechanical and corrosion resistance and thereby widely used in a variety of industries and environments due to its outstanding properties such as mechanical and corrosion resistance. These materials, which are usually considered difficult to weld by conventional fusion welding processes, have demonstrated outstanding performance when joined by Friction Stir Welding (FSW), a solid-state joining process. FSW input energy regulates the magnitude of the thermal cycle and the intensity of deformation during the process, and it can be controlled by the welding parameters, which affects the grain features and consequently the mechanical properties of the joints. The aim of this work is to evaluate the feasibility of producing friction stir welds of a 304 austenitic stainless steel and correlate this process to the microstructures and mechanical properties in these joints. The samples were produced using a polycrystalline cubic boron nitrides (PCBN) tool and four different rotational speeds. Microstructural investigation showed that all joints presented, besides the base material (BM), the three typical FSW zones: stir zone (SZ), termomecanically affected zone (TMAZ) and heat affected zone (HAZ). The ZTA exhibited a microstructure similar to MB, while ZTMA and ZM were characterized by dynamic recovery and recrystallization, respectively. In the advancing side of ZM was observed the formation of sigma phase, a brittle and undesirable phase. The welding parameters variation affected mainly the deformation experienced by the material, the average grain size and length of the weld zones. The mechanical tests were consistency with the observed microstructures, being the mechanical properties of joints higher than BM, which is very attractive from the technological point of view.
Os aços inoxidáveis são uma importante classe de materiais de engenharia que possuem propriedades atrativas, como a alta resistência mecânica e a corrosão, sendo extensamente aplicados em muitas indústrias e em diversos ambientes. Esses materiais, frequentemente considerados difíceis de serem soldados pelos métodos de soldagem por fusão convencionais, têm demonstrado um excelente desempenho quando unidos pela técnica de soldagem por fricção e mistura (FSW Friction Stir Welding), um processo de soldagem no estado sólido. Na FSW, a energia do processo determina a magnitude do ciclo térmico e a intensidade da deformação que ocorre no material durante o processo energia essa controlada pelos parâmetros de soldagem afetando características do grão e consequentemente as propriedades mecânicas das juntas. O presente estudo tem por objetivo avaliar a viabilidade de união de placas de aço inoxidável austenítico AISI 304 e relacionar processo, microestruturas e propriedades mecânicas nestas soldas. As amostras foram produzidas utilizando-se uma ferramenta de nitreto de boro cúbico (PCBN) e quatro diferentes velocidades de rotação da ferramenta. A observação microestrutural mostrou que as soldas produzidas apresentam além do metal de base (MB), três zonas típicas do processo FSW: zona de mistura (ZM), zona termomecanicamente afetada (ZTMA) e zona termicamente afetada (ZTA). A ZTA apresentou uma microestrutura similar ao MB, enquanto que ZTMA e a ZM foram caracterizadas por recuperação e recristalização dinâmica, respectivamente. No lado de avanço da ZM houve a formação de fase-, frágil e indesejada. A variação dos parâmetros de processo afetou principalmente o tamanho médio de grãos, a deformação sofrida pelo material e a extensão das zonas de soldagem. Os resultados dos ensaios mecânicos demonstraram coerência com as microestruturas observadas, de forma que as propriedades mecânicas das juntas soldadas foram superiores ao MB, sendo dessa forma atraentes do ponto de vista tecnológico.

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Demmouche, Younes. "Étude du comportement en fatigue d'assemblages soudés par FSW pour applications aéronautiques." Phd thesis, Paris, ENSAM, 2012. http://pastel.archives-ouvertes.fr/pastel-00838617.

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La course à l'allègement des aéronefs constitue aujourd'hui l'un des enjeux principaux de l'industrie aéronautique. Le remplacement des rivets par des soudures FSW sur les voilures permettrait de gagner jusqu'à 20% de la masse totale de la voilure. Ce travail réalisé en collaboration avec Dassault-Aviation s'inscrit dans le cadre du projet ADSAM (Assemblage de Structures Aéronautiques Métalliques) visant à fabriquer un démonstrateur de caisson de voilure soudé par FSW. Cette étude traite du comportement mécanique en traction monotone quasi-statique et en fatigue oligocyclique (10⁴ à 10⁵ cycles) d'alliages d'aluminium (séries 2000 et 7000) soudés par FSW. L'objectif est d'étudier l'effet des hétérogénéités microstructurales induites par le soudage sur les hétérogénéités de comportement mécanique dans les joints soudés. La corrélation d'images numériques a été utilisée pour définir la réponse mécanique (σnominale - εvraie) dans chacune des zones constituant ces soudures. En complément, des essais sur des mini-éprouvettes prélevées dans l'épaisseur des joints ont permis d'établir le comportement local (σvraie - εvraie) dans chacune des zones du joint. Sous chargement de traction monotone, la rupture des soudures FSW a été observée dans la zone de localisation des déformations anélastiques située aux minima des profils de microdureté. En revanche, les fissures de fatigue ne démarrent pas nécessairement dans ces zones de localisation. Des analyses microscopiques des faciès de rupture ont permis d'identifier deux mécanismes principaux d'amorçage de fissure : (i) rupture ou (ii) décohésion de particules intermétalliques. D'autre part, les essais cycliques montrent une adaptation élastique des matériaux dans les différentes zones du joint (noyau, ZAT et ZATM) après stabilisation autour d'une déformation moyenne non nulle. En terme de durée de vie, les résultats d'essais sur éprouvettes entaillées traitées OAC (représentative de zones critiques sur structure) montrent que le soudage par FSW réduit jusqu'à 50% la tenue en fatigue de ces alliages. L'amorçage des fissures de fatigue est dû aux piqûres créées par le traitement d'OAC. Les résultats obtenus dans le cadre de ce travail ouvrent des perspectives intéressantes pour modéliser le comportement mécanique des joints soudés par FSW afin d'estimer leur durée de vie en fatigue oligocyclique.

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Granat, Simon. "Naturvårdsuppföljning vid slutavverkningar : En jämförelse mellan FSC-certifierade bolag i södra Sverige." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-54015.

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Today biodiversity is an important issue in forestry, and it should be considered in all silvicultural measures. Follow-up of nature conservation should also be done by FSC certified companies after i.e. final fellings. The purpose of this study was to describe the results of the nature conservation made by three companies in southern Sweden, their methodology of follow-up, to find out if there is a relation between the results of the follow-up and the methodologies used, and to describe the companies own opinions. Both the proportion of approved final fellings and the methodology of follow-up differed between the companies. One company differed from the others regarding the measurement of the volume of deciduous trees. The companies also differed in how they put together the final results of the follow-up. It might be a correlation between the proportion of approved final fellings and the methodology used.

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Almeida, Renato Caldas Vasconcellos de. "Análise numérica de falha de vigas de KUHN fabricadas com soldagem FSW." Instituto Tecnológico de Aeronáutica, 2012. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3324.

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O objetivo deste trabalho é propor modelos em elementos finitos que sejam capazes de descrever o comportamento do elemento estrutural representativo conhecido por Viga de Kuhn, quando este é fabricado pelo processo de união permanente intitulado Solda por Atrito - FSW (Friction Stir Welding), quando comparado a modelos analíticos. Inicialmente, faz-se uma ampla revisão bibliográfica dos trabalhos de autores diversos. Desta, originou-se uma descrição do processo de solda FSW, sua viabilidade como processo e seu potencial para a indústria aeronáutica. Ainda, seguiu-se a descrição da Viga de Kuhn, com foco de interesse no estudo do regime de pós-flambagem. São apresentados os métodos analíticos de análise de flambagem e pós-flambagem seguida de falha, tendo a literatura clássica para junções rebitadas como fundamento. Foram desenvolvidos três modelos de Elementos Finitos para o estudo computacional que incorporam junções com o objetivo de simular a soldagem FSW. São confrontados os resultados analíticos e computacionais como forma de melhor compreender o comportamento em pós-flambagem da viga.

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Lorrain, Olivier. "Analyses expérimentales et numériques du procédé de soudage par friction malaxage fsw." Paris, ENSAM, 2010. https://pastel.archives-ouvertes.fr/pastel-00515112.

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Le soudage par friction malaxage FSW est un procédé de soudage à l'état solide, sans fusion du matériau. La soudure est réalisée par l'action d'un outil composé d'un épaulement et d'un pion positionné à l'interface des deux pièces à souder. L'outil a deux rôles : échauffement de la matière par frottement de l'épaulement, malaxage de la matière par l'intermédiaire du pion. Ce travail de thèse s'inscrit dans le cadre d'un partenariat entre Arts et Métiers ParisTech et l'Institut de Soudure. Son objectif est de développer un modèle de simulation du FSW afin de réduire le nombre d'essais expérimentaux nécessaire à l'optimisation du procédé. Ainsi, plusieurs points ont été abordés dans ce manuscrit. Une analyse expérimentale des cycles thermiques et des mouvements de matière dans le cas où les pions sont non filetés a été menée. Cette situation permet (1) de faciliter la comparaison avec la simulation numérique et (2) de se placer dans les conditions de pions usés. L'analyse des formulations (lagrangienne, eulérienne et ALE) en vue de choisir celle la plus appropriée pour représenter les écoulements de matière a permis de retenir une formulation eulérienne (mise en œuvre dans le logiciel FLUENT) pour estimer les champs thermiques et de vitesses à l'état stationnaire. La mise en place d'un modèle numérique dans le logiciel FLUENT est présentée. Nous avons en particulier étudier l'influence des paramètres numériques sur les résultats et mis en place une stratégie d'identification de certains paramètres non accessibles expérimentalement. Une comparaison fine entre nos résultats expérimentaux et ceux issus des simulations a été effectuée avec succès. L'étude de l'impact des paramètres process (vitesse d'avance, vitesse de rotation) et de la géométrie du pion sur les champs thermiques et de vitesses a permis de mettre en évidence le lien entre les champs de vitesse et la présence de défauts de type tunnel
The Friction Stir Welding (FSW) is a solid state welding process, without melting. The weld is fabricated thanks to the action of tool made of a shoulder and a pin, positioned at the interface of the two pieces to be welded. The tool as two roles : heating of the material by friction of the shoulder, mixing of the material due to the pin. This thesis work is made within the partnership between Arts et Métiers ParisTech and Institut de Soudure. Its goal is to develop a FSW simulation model in order to decrease experimental trials required to optimize the process. Therefore, some points have been treated in this manuscript. Experimental analysis of thermal cycles and material movements in the case of unthreaded tools has been carried out. This situation allows (1) to make the comparison with numerical simulation easier and (2) to be in the case of worn tools. Formulations (lagrangian, eulerian, ALE) analysis in order to choose the more appropriate to take material flow into account has allowed to select an eulerian formulation (implemented in the FLUENT software) to estimate thermal and kinematical fields in the steady state. The set up of the numerical model in the FLUENT software is presented. We have studied the influence of numerical parameters on the results and proposed an identification strategy for some parameters which are not reachable experimentally. A detailed comparison between our experimental results and the ones from our simulations have been performed with success. The study of the influence of the process parameters (feed rate, rotating speed) and of the pin geometry on the kinematical and thermal fields has highlighted the link between velocity field and the presence of tunnel type defects

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Huang, Dongfang. "Investigation of heterogeneity of FSW Inconel 718 coupled with welding thermal cycles /." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd2750.pdf.

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Morrone, Ericka Pardini. "Contribuições da auditoria ambiental para a comunicação do desempenho de empresas com certificação FSC : análise das não conformidades evidenciadas no resumo público de auditoria." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/100/100136/tde-20042016-184147/.

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O trabalho teve como objetivo analisar como as empresas comunicam ao público externo, por meio do resumo público de auditoria, suas dificuldades (representadas pelas não conformidades) para atender aos requisitos socioambientais da certificação FSC. Foi considerada a influência da configuração da auditoria na comunicação às partes externas. Foram coletados dados secundários de 95 resumos públicos das auditorias executadas entre 2010 e 2015, analisados pela técnica da análise de conteúdo com o intuito de identificar as principais áreas temáticas as quais as não conformidades evidenciadas se referiam, sendo mapeado um total de onze áreas temáticas. Com base em análise estatística descritiva (testes de Kruskal Wallis e Chi quadrado) buscou-se identificar as relações entre as características das auditorias definidas (Tamanho da equipe auditora, Diversidade na formação da equipe, Tempo de auditoria, Empresa certificadora e Evento de auditoria) e as áreas temáticas identificadas. Atendimento à legislação do trabalho; Plano de manejo; Qualidade do monitoramento do sistema; e Comunicação e relacionamento com o público foram as áreas temáticas com maior quantidade de não conformidades. Identificou-se que, com exceção de casos específicos, não há relações significativas entre as características das auditorias e a comunicação de não conformidades. No entanto, isso não quer dizer que a maneira como a auditoria ocorre não influencie a qualidade dos resultados obtidos, pois há outros fatores, como a qualidade e veracidade das não conformidades apontadas, a ser considerados. Os relatórios públicos de auditoria representam um avanço na comunicação dos resultados socioambientais obtidos, que convergem com a necessidade de transparência da certificação. Entretanto, há de se evoluir na busca da divulgação de resultados de maneira mais clara e organizada e na relação com comunidades do entorno dos empreendimentos florestais
The study aimed to analyze how companies communicate to the public through the public summary of audit their difficulties (represented by the non-conformities) to meet the environmental requirements of FSC certification. The influence of the configuration of the audit was considered on the results obtained in the process, results these communicated to external parties. We collected secondary data from 95 public summaries carried out between 2010 and 2015, analyzed by the content analysis technique in order to identify the main thematic areas which non-conformities referred, and mapped a total of eleven thematic areas. Based on descriptive statistical analysis (Kruskal Wallis test and Chi square) sought to identify the relationship between the characteristics of the audits defined (Size of the audit team, Diversity in the training of staff, Audit time, Certifying company and Audit event) and thematic areas identified. The Compliance with labor legislation; Management plan; Quality of system monitoring; Communication and relationship with the public were the thematic areas with the highest number of non-conformities. It was found that, except for specific cases, there is no significant relationship between the characteristics of the audits and the disclosure of non-conformities. However, this does not mean that the way the audit happen not influence the quality of the results, as there are other factors such as the quality and truthfulness of non-compliances identified to be considered. Public reports represent a breakthrough in communication of socioenvironmental results obtained, converging with the need for transparency in the certification. However, is necessary to evolve in pursuit of disseminating results in a more clear and organized way and at the relation with the communities that surrounding enterprise

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Grund, Olof. "Modification of a transient EPR and photoluminescence detection setup." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-328896.

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Climate change has given rise to higher demand of renewable energy. Conventional non-organic solar cells are still seen the most on the market but the last 10-20 years there has been an exponential increase in research about organic solar cells. The research demands measurements done on increasing fast time scales as insights about the topic and technology develops. Here is presented configurations done at the Isaak spectrometer at Freie Universit\"{a}t Berlin. The spectrometer is used for studying charge transport in organic solar cells as well as hybrid solar cells made from organic and inorganic semiconductors. One important feature for the time response is the Q factor property of the resonator in which the sample is placed. The Q factor describes the rate of energy loss relative to the stored energy of the resonator. The Q factor dependency over different temperature was studied in order to gain vital knowledge about the time response of the setup. Further new equipment was been installed at the setup and programmed in FSC2. This in order to increase the sensitivity of the optical setup, secure the personnel from possible dangerous excitation laser and in order to do more automated measurements. As the optical path was modified by installing a new optical fiber a new calibration had to be done. Finally, in order to try the functionality of the new equipment an automated energy dependency measurement was done on the polymer MEH-PPV and the polymer:fullerene blend MEH-PPV:PCBM. The automatic process of measuring was successful.

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Hasan, Ahmed Falh. "Modelling of tool wear and metal flow behaviour in friction stir welding (FSW)." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/36154/.

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Friction Stir Welding (FSW) is a solid-state joining process that was invented in 1991; it is particularly useful for joints difficult to make using fusion techniques. Significant advances in FSW have been achieved in terms of process modelling since its inception. However, until now experimental work has remained the primary method of investigating tool wear in FSW. In this project, two main objectives were set; the first one was to produce a numerical approach that can be used as a useful tool to understand the effect that worn tool geometry has on the material flow and resultant weld quality. The second objective was to provide a modelling methodology for calculating tool wear in FSW based on a CFD model. Initially, in this study, a validated model of the FSW process was generated using the CFD software FLUENT, with this model then being used to assess in detail the differences in flow behaviour, mechanically affected zone (MAZ) size and strain rate distribution around the tool for both unworn and worn tool geometries. Later, a novel methodology for calculating tool wear in FSW is developed. Here a CFD model is used to predict the deformation of the highly viscous flow around the tool, with additional analysis linking this deformation to tool wear. A validation process was carried out in this study in order to obtain robust results when using this methodology. Once satisfied with the tool wear methodology results, a parametric study considering different tool designs, rotation speeds and traverse speeds was undertaken to predict the wear depth. In this study, three workpiece materials were used which were aluminium 6061, 7020 and AISI 304 stainless steel, while the materials used for the tools used were of H13 steel and tungsten-rhenium carbide (WRe-HfC) with different tool designs. The study shows that there are significant differences in the flow behaviour around and under the tool when the tool is worn and it shows that the proposed approach is able to predict tool wear associated with high viscous flow around the FSW tool. With a simple dome shaped tool, the results shows that the tool was worn radially and vertically and insignificant wear was predicted during welding near the pin tip. However, in other regions the wear increased as the weld distance increased. Additionally, from the parametric study that was undertaken for the two tool designs - a dome and a conical shape- the study has found that for both tool designs, wear depth increases with increasing tool rotation speed and traverse speed. It was also shown that, generally, the wear depth was higher for the conical tool design than the dome tool in the pin tip zone. The research concludes that a proposed methodology is able to calculate tool wear associated with high viscous flow around the FSW tool, which could be used as a method for calculating tool wear without the need for experimental trials. The CFD model has provided a good tool for prediction and assessment of the flow differences between un-worn and worn tools, which may be used to give an indication of the weld quality and of tool lifetime. Furthermore, from the results, it can be concluded that this approach is capable of predicting tool wear for different process parameters and tool designs and it is possible to obtain a low wear case by controlling the process parameters.

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Yeung, Wai-man Violet, and 楊慧敏. "The popularity of FSC timber products in the consumer market in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/207622.

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This study was conducted to examine the availability of certified timber products in the consumer market in Hong Kong and the popularity of FSC timber products in the Hong Kong consumer market. Consumers’ level of environmental friendliness; their view of the use of timber to the environment; the factors affecting their choice of timber for household renovation; their awareness on the term “FSC” and the kind of FSC products they are aware of; consumers’ willingness-to-pay (WTP) and WTP premium level for FSC products in Hong Kong, are studied. Moreover, the effectiveness of various kinds of marketing and promotion techniques FSC could adopt in Hong Kong, are reviewed. Site investigations to the “renovation streets” in Wanchai and Mongkok were carried out and it is found that a high percentage of wooden floorings shops (79% in Wanchai and 77% in Mongkok) carry products with the timber certification logos (FSC and/or PEFC). Despite this significant percentage of shops carrying products with the timber certification logos, it is also found that there is generally a lack of awareness amongst the shopkeepers on the FSC labels/logos that are shown on their products. For the online questionnaire survey, a total of 146 questionnaires werecollected and the study revealed that 25% of the respondents areaware of the term “FSC”. While 80% of the participants thought that the use of timber products for flooring and furniture for household renovation have an adverse impact to the natural environment, the impact to the environment is not the main factor that will affect people's purchase decision. The majority of respondents (68%) indicated that they “Only generally aware of the term ‘FSC timber products’ or equivalent terms” and FSC paper is the major kind of FSC products they have heard of. For the WTP for a premium for FSC timber products, 47% of the respondents agree with a premium; the majority of respondents (72%) opted for a 0-10% WTP premium with a mean premium WTP level of 9.06%. Based on the literature review and study, it could be concluded that the awareness of the FSC certifications, together with the availability of FSC certified timber products in the consumer market, are the keys to create market demand for FSC products. And it could be done via efforts from environmental NGOs by persuading businesses to choose certified timber products and educating consumers to raise their awareness of FSC products. Together with efforts from FSC to be more proactive via online media as well as creating new labels for retailers, it is hoped that the popularity of FSC products in Hong Kong could be enhanced.
published_or_final_version
Environmental Management
Master
Master of Science in Environmental Management

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Terreros, Iñigo. "Modélisation DEM thermo-mécanique d'un milieu continu. Vers la simulation du procédé FSW." Phd thesis, Ecole nationale supérieure d'arts et métiers - ENSAM, 2013. http://pastel.archives-ouvertes.fr/pastel-00996971.

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De nos jours, la gestion des flux de matière autour de la zone decontact représente un des principaux verrous scientifiques pourl'amélioration des simulations des procédés d'usinage comme, parexemple, le procédé FSW. Les méthodes basées sur la mécanique desmilieux continus sont couramment utilisées dans ces simulations maiselles rencontrent de nombreuses difficultés dans les zones decontact. Une explication "physique" à ces difficultés estl'utilisation des équations issues de la mécanique des milieuxcontinus pour décrire des phénomènes discontinus. À ce point, laméthode des éléments discrets s'est révélée être une alternative auxapproches continues pour traiter le problème causé par cesdiscontinuités. Cette méthode est en revanche très gourmande en termede temps de calcul.Une solution à long terme passe par un couplage entre méthodescontinues et discrètes qui requiert une zone de recouvrement où lesdeux approches coexistent. Cette zone est classiquement placée dansune région continue et cela oblige à développer la méthode deséléments discrets pour qu'elle puisse opérer dans ce type derégion. Le travail de thèse présente une méthode pour simuler laconduction de la chaleur et le comportement mécanique des milieuxcontinus élasto-plastiques. Cette méthode peut travailler dans la zonecontinue de recouvrement et, en plus, elle peut être facilementcouplée avec les méthodes discontinues classiques.Le couplage entre l'aspect thermique et l'aspect mécanique estégalement étudié et comparé aux résultats expérimentaux issus de labibliographie.

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Sonne, Lehnberg Ida. "Privata skogsägares uppfattning om FSC- och PEFC-certifiering : att bli och vara certifierad." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76666.

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Syftet med studien var att beskriva och analysera hur Sydveds certifieringsprocess upplevs av företagets virkesleverantörer. Studien genomfördes som en enkätundersökning via post och e-post. De frågeställningar som utgjorde stommen av arbetet handlade huvudsakligen om upplevelsen kring certifieringsprocessen, virkesleverantörernas kunskap om certifiering, motiv till certifiering och hur dessa påverkar upplevelsen av certifieringsprocessen. Fokus låg även på huruvida den geografiska spridningen hade någon betydelse för upplevelsen liksom om virkesleverantörerna upplevde ett behov av en förändring i certifieringsprocessen. Sammanfattningsvis visade resultaten främst på en förbättringspotential gällande återkoppling och kunskap. Det som Sydved rekommenderas att utveckla är olika delar av certifieringsprocessen där tyngdpunkten bör ligga på att få ett enhetligt sätt att jobba på inom organisationen. Hela certifieringsprocessen, från introduktion till revision och återkoppling bör ha tydliga riktlinjer, då kedjan inte är starkare än sin svagaste länk.

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Fioravanti, Artur Suárez. "Soldagem por FSW de ligas de alumínio Alcalad AA2024-T3 e AA7075-T6." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2008. http://hdl.handle.net/10183/14373.

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A soldagem das ligas de alumínio AA2024-T3 e AA7075-T6 sempre foi um obstáculo para indústria devido à alta suscetibilidade a trincas durante o processo de soldagem ao arco elétrico. Estas ligas são largamente utilizadas na indústria aeronáutica devido a sua alta resistência mecânica e baixo peso específico do alumínio, sendo que o método de união mais utilizado é a rebitagem. Com o advento da soldagem por FSW, surge uma nova oportunidade de união destas ligas sendo que os estudos apresentados até o momento demonstram excelentes propriedades mecânicas da junta. “Friction Stir Welding” – FSW é uma técnica de soldagem desenvolvida em 1991 pelo “The Welding Institute” (TWI) na Inglaterra. Esta solda tem a vantagem de ocorrer no estado sólido, que preserva as propriedades mecânicas das ligas, ao contrário dos métodos de soldagem convencionais que envolvem fusão e produzem, em grande parte, microestruturas com baixas propriedades mecânicas. No processo FSW uma ferramenta de alta resistência mecânica com um determinado perfil é rotacionada de forma a gerar atrito nas peças a serem soldadas. Este atrito gera calor suficiente para aumentar a ductilidade e misturar o material na junta, consolidando o mesmo, sem a ocorrência de fusão. O objetivo deste trabalho é determinar um conjunto de parâmetros através do processo FSW, para soldagem de chapas das ligas Alclad AA2024-T3 e AA7075-T6 com 1,8 mm de espessura, utilizando uma fresadora universal de alta rigidez. Para isso foram desenvolvidas duas geometrias de ferramentas para os quais um conjunto de parâmetros resultasse em soldas livres de defeitos. Uma vez obtidas estas soldas, as mesmas foram testadas através da medição de microdureza, ensaios de dobramento e tração para verificação das propriedades mecânicas resultantes comparadas ao do metal base. Observou-se que algumas juntas, dependendo dos parâmetros e da ferramenta utilizados, não demonstraram ductilidade adequada durante os ensaios de dobramento, embora não apresentassem defeitos na análise macrográfica. Da mesma forma, a resistência mecânica apresentada pelas mesmas atingiu no máximo 70% do metal base, demonstrando ser a técnica, uma boa alternativa a rebitagem. Por fim, para liga AA2024-T3, pode-se obter um conjunto de parâmetros que resultasse em uma solda com as propriedades finais desejadas, ou seja, livre de defeitos, ductilidade adequada e boa resistência à tração.
The welding of AA2024-T3 and AA7075-T6 clad aluminum alloys was always an obstacle to the industry due to cracking susceptibility during arc welding process. These alloys are largely used in the aeronautical industry because of their high mechanical strength and low density, being riveting the most widely used method to join them. The advent of friction stir welding (FSW) presents itself as a new opportunity to join these alloys and the present research demonstrates excellent mechanical properties of the joint. Friction stir welding is a welding technique that was developed in 1991 at The Welding Institute (TWI) in England. This welding method has the advantage to be a solid state process that preserves the mechanical properties of alloys, to the contrary of conventional fusion welding techniques that produce microstructures with low mechanical properties. In the FSW process a high strength tool with a given profile is rotated in order to generate friction in the parts to be welded. This friction generates enough heat to soften and stir the material, joining them without fusion. The objective of this work is to determine a set of parameters using the FSW process to weld a 1,8 mm thick AA2024-T3 and AA7075-T6 aluminum clad sheet using a stiff milling machine. For this purpose, development of two tool geometries with a set of parameters to obtain defect-free welded joints was utilized. These welded joints were investigated using microhardness, bending and tension testing to verify the mechanical properties in comparison with the base metal. It was noted that, dependent upon the parameters and tools used for welding, the joints did not show adeq uate ductility during the bending testing, even if the macrographic analysis demonstrate no defects. In the same way, the joint mechanical strength is 70% of base metal, showing that this technique is a good alternative for riveting method. Finally, for the AA2024-T3 aluminum alloy, it was obtained the desired properties for the joints, with no defects, good ductility and tension strength.

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Mattiello, Rafael. "As trajetórias da certificação florestal dos standards do Conselho de Manejo Florestal - FSC." Florianópolis, 2012. http://repositorio.ufsc.br/xmlui/handle/123456789/100992.

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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Sociologia Política.
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O objetivo geral desta tese é contribuir ao crescente corpo teórico da sociologia ambiental. A teoria da modernização ecológica trata da necessidade de readequação ambiental oriunda dos principais atores envolvidos nos processos de crescimento e desenvolvimento industrial do capitalismo contemporâneo. Argumentamos que a modernização ecológica está relacionada à emergência de práticas responsáveis por intermédio da construção de standards por autoridades privadas especializadas. Analisamos as transformações sociais que permitiram a introdução de mecanismos privados de manejo florestal responsável e suas implicações político-sociológicas através de um estudo de caso dos processos e conflitos em torno dos standards do Conselho de Manejo Florestal - FSC. Defendemos que a (alta)modernidade sob uma condição de globalização se caracteriza por riscos e incertezas, demandas e expectativas, necessidades e oportunidades intrínsecas à própria dinâmica de reflexividade deste fenômeno, o que gera novas possibilidades e reanálises em todos os âmbitos. As empresas standards foram criadas, implementadas e cada vez mais legitimadas por todos para estabelecer novas práticas econômicas/administrativas/fabris/ socioambientais que dessem conta da expectativa da sociedade como um todo. Dentro desta abordagem caracterizada pelos fluxos, redes e pela modernização reflexiva/ecológica é analisada a emergência e o desenvolvimento do standard de manejo florestal mais respeitado e amplamente utilizado pela indústria de madeira, papel, celulose e embalagens, gráficas - os standards do FSC, com seus conflitos e discrepâncias nesta ampla rede de atores sociais in-the-making, através de duas etapas de certificação florestal: a definição de normas e a implementação delas. São analisadas as certificações da Klabin (realizada pelo Imaflora) e da Veracel (realizada pela SGS) e ao mesmo tempo as características reflexivas, conflituosas, ideológicas e discursivas destes standards. Por fim são dadas algumas recomendações para serem debatidas visando o aprimoramento característico e contínuo do sistema FSC.
The aim of this thesis is to contribute to the growing body of literature on environmental sociology. The theory of ecological modernization exposes the need for environmental adjustment of the main actors involved in the processes of industrial growth and development of contemporary capitalism. We argue that ecological modernization is related to the emergence of responsible practices through the construction of private standards by specialized authorities. Hence, we analyze the social changes that allowed the introduction of private mechanisms for responsible forest management and its implications in a political-sociological study of the processes and conflicts involved in a case study of the Forest Stewardship Council standards. We contend that the (high)modernity under a condition of globalization is characterized by risks and uncertainties, demands and expectations, needs and opportunities inherent to the dynamics of this phenomenon of reflexivity, which creates new possibilities and reanalysis in all areas. Specifically business standards were created, implemented and increasingly legitimized to establish new economic/administrative/ manufacturing/socioenvironmental practices that account to the expectation of the entire society as a whole. Within this approach characterized by flows, networks and through the theory of reflexive/ ecological modernization we analyze the emergence and development of the forest management standard that is most respected and widely used by the wood, pulp and paper, packaging and printing industries - the standards of the FSC. We focused in the conflicts and discrepancies of this extensive network of social actors in-the-making through the two stages of forest certification: setting the standards and its implementation. Thus, it is considered the certification of Klabin performed by Imaflora (SmartWood/Rainforest Alliance) and Veracel conducted by SGS, while it analyzes the reflexive, conflicted, ideological and discursive characteristics of those standards. Finally some recommendations are given to be discussed aiming at the characteristic continuous improvement of the FSC system.

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Tchein, Gnofam Jacques. "Étude des couplages thermomécaniques et microstructuraux d’un alliage de titane au cours du soudage FSW." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0344/document.

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Le soudage FSW (Friction Stir Welding) est un procédé de soudage à l’état solide appliqué aujourd’hui dans les secteurs des transports aérospatial, naval et ferroviaire. Il présente l’avantage de fournir des soudures aux propriétés mécaniques meilleures que celles des procédés de soudage par fusion de la matière. La plupart des études menées sur ce procédé concernent les alliages d’aluminium. Ce travail porte sur l’étude des phénomènes thermomécaniques et métallurgiques pendant le procédé de soudage FSW du TA6V. L’influence de la microstructure initiale sur les propriétés mécaniques et la microstructure finale est étudiée à travers une étude expérimentale. La ZAT et la ZATM des soudures ont une très faible épaisseur et les soudures ne présentent pas de zone de fragilité. La genèse de la microstructure pendant le soudage a été identifiée et s’articule en trois points: changement de phase α → β, recristallisation dynamique continue de la phase β, formation de grains α à l’intérieur des grains β recristallisés. Afin de mettre en place un modèle permettant de prédire la microstructure dans le noyau de la soudure, des essais de torsion à chaud ont été réalisés pour déterminer les propriétés rhéologiques du TA6V. Ces essais ont aussi permis de mettre en place une loi de comportement analytique du TA6V. Les champs de vitesse sont formulés analytiquement à partir des équations de la mécanique des fluides et les champs thermiques sont déterminés numériquement à partir d’une formulation eulérienne
Friction Stir Welding (FSW) is a solid state welding process used today in the aerospace, naval and rail transport sectors. It has the advantage of providing welds with better mechanical properties than fusion welding processes. Most of studies carried out on this process concern aluminum alloys. This work focuses on the study of thermomechanical and metallurgical phenomena during FSW of the Ti-6Al-4V alloy. The influence of the initial microstructure on the mechanical properties and the final microstructure is studied through an experimental study. The HAZ and TMAZ of the welds are very thin and the welds didn’t present any weak zone. The genesis of the microstructure during the process has been identified and is made up with three main steps: α → β phase change, continuous dynamic recrystallization of the β phase and formation of α grains within the recrystallized β grains. In order to set up a model to predict the microstructure in the weld nugget, hot torsion tests were performed to determine the rheological properties of TA6V. These tests also made it possible to set up an analytical behavior law of Ti-6Al-4V. The velocity fields during FSW are formulated analytically from the equations of fluid mechanics and thermal fields are determined numerically from a eulerian formulation

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Saunier, Valentin. "Microélectrodes nanocomposites implantables couplant enregistrement-stimulation neuronale et détection électrochimique de neurotransmetteurs." Thesis, Toulouse 3, 2021. http://www.theses.fr/2021TOU30023.

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L'électrophysiologie est le domaine de la physiologie qui vise à enregistrer l'activité électrique des tissues biologiques. En utilisant des microélectrodes implantées dans le cerveau, l'électrophysiologie a permis de réaliser des avancées décisives dans la compréhension des mécanismes neurologiques majeurs, comme la mémoire, le langage et l'apprentissage, grâce à l'enregistrement de l'activité électrique du cerveau. Ces avancées promettaient d'aider au développement de traitements et de dispositifs thérapeutiques pour les principales maladies neurologiques comme Parkinson, Alzheimer ou l'épilepsie. Cependant, la nécessité d'obtenir des sources de signaux complémentaires aux enregistrements électrophysiologiques a récemment émergé, la recherche thérapeutique basée exclusivement sur l'utilisation de ces signaux électriques conduisant le plus souvent à des impasses. Ces signaux électriques étant portés par des molécules appelées neurotransmetteurs, leur détection en temps réel devrait être une source pertinente de signaux complémentaires à combiner aux signaux électrophysiologiques. Durant cette thèse, de nouvelles microélectrodes nano-composites à base de PEDOT et de nanofibres de carbone oxydées ont été développées pour réaliser cette combinaison. Ces électrodes présentent d'excellentes caractéristiques in-vitro pour l'électrophysiologie bidirectionnelle, avec une faible impédance et une forte capacité d'injection de charge. Ces électrodes permettent également de détecter électrochimiquement la dopamine (un neurotransmetteur clé) grâce à deux techniques complémentaires, la chronoampérométrie et la voltammétrie cyclique rapide. De plus, ces électrodes modifiées gardent un profil spatial adéquat pour s'interfacer avec une cellule unique, ce qui ajouté à leurs autres caractéristiques en font des dispositifs adéquats pour l'interfaçage neuronal multifonctionnel, ajoutant la détection de neurotransmetteurs à l'enregistrement électrique. Intégrées sur des implants flexibles, ces électrodes ont été testées in-vivo dans des tranches de cerveau de souris comme électrodes d'enregistrement et de stimulation électrique, réalisant de l'électrophysiologie bidirectionnelle. Leurs hautes performances ont permis d'enregistrer l'activité électrique du cerveau sur une plage de fréquences plus importante et avec un meilleur rapport Signal sur Bruit que celui obtenu avec des microélectrodes standard. En conclusion, les performances des microélectrodes modifiées développées durant cette thèse sont très prometteuses pour l'interfaçage neuronal multifonctionnel au niveau de la cellule unique. Elles permettent en effet le couplage d'enregistrements électrophysiologiques et de stimulation électrique in-vivo, tout en permettant la détection électrochimique de neurotransmetteurs in-vitro. Ces propriétés en font des dispositifs de pointe pour la recherche et pour des applications thérapeutiques en neuroscience faisant appel à la fois à l'enregistrement des activités électrique et neurochimique
Electrophysiology is the physiology field that aims at recording the electrical activity of biological tissues. Using microelectrodes in or on the brain, electrophysiology helped make crucial advancements in the understanding of major neurological mechanisms like memory, language, learning by recording the brain electrical signals. Through these advances, it promised and helped develop treatments and therapeutic devices to cure the major neurological diseases like Parkinson's, Alzheimer's or epilepsy. However, recently the need for other sources of information to combine with electrophysiological recordings has raised, as the research and therapeutic approaches over-relying on these recordings did mostly lead to dead-ends. As the brain electrical activity is molecularly supported by a class of molecules called neurotransmitters, their detection in real-time is proposed as a high-potential complementary brain study technique to integrate along with electrophysiological recordings during neural interfacing. During this PhD, we developed a new generation of nanocomposite microelectrodes made of both PEDOT and oxidized carbon nanofibers to meet this combined integration. These electrodes displayed a key characteristics combination in-vitro, with low impedance, high charge injection limit, making them promising candidates for bidirectional electrophysiology, while being capable to detect dopamine (one key neurotransmitter) using two complementary techniques, chronoamperometry and fast-scan cyclic voltammetry. Moreover, these electrodes keep a sufficiently low spatial profile to interface with single cells, making them promising candidates for multifunctional neural interfacing, adding neurochemical detection to electrical recordings. Integrated on flexible implants, these electrodes were first tested in-vivo in brain slices as recording and stimulating electrodes (realizing bidirectional electrophysiology). They showed high performances, being capable to record brain electrical signals on a wider frequency range than standard microelectrodes, with a higher Signal to Noise Ratio (SNR). They also allowed to electrically stimulate brain slices tissues, generating measurable outputs with low inputs compared to standard electrodes. In conclusion, the modified electrodes developed in this thesis showed promising properties for multifunctional neural interfacing at a single cell level, enabling the coupling between electrophysiological recording and electrical stimulation of tissues in-vivo, while also being capable of neurotransmitter electrodetection in-vitro. Through these properties, they constitute meaningful candidates for long-term simultaneous recording of the brain electrical and neurochemical activities for research and therapeutic applications

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Silva, Erenilton Pereira da. "Fundição, laminação e soldagem por fricção e mistura mecânica de ligas de magnésio com adição de Mischmetal." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/18/18158/tde-09022017-081216/.

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A crescente escassez de recursos energéticos renováveis bem como o aumento contínuo dos seus custos, tem requerido uma redução drástica no consumo de energia utilizada para o transporte de cargas e passageiros nas últimas décadas. Uma alternativa é a redução de peso com a utilização de ligas leves em substituição às ligas convencionais utilizadas no setor de transporte. Nesse conceito o uso de ligas de magnésio é justificado pela sua baixa densidade. Dentre as ligas de magnésio, a matriz ASTM série ZK é a que apresenta maior resistência mecânica e a adição de elementos de terras raras (RE) elevam a resistência à corrosão, a temperatura de trabalho e o limite de escoamento, devido à formação de filmes de óxidos finos e densos, além de intermetálicos de alto ponto de fusão e de maior dureza. A formação de intermetálicos do tipo MgZn de baixo ponto de fusão, torna as ligas de matriz do tipo ZK susceptíveis à formação de trinca à quente durante a soldagem, inviabilizando o uso de processos de soldagem convencionais. Uma alternativa é a solda por fricção e mistura mecânica (SFMM) realizada abaixo da temperatura de fusão. Neste trabalho, foram produzidas ligas ZK60, ZK60-1,5RE (liga ZK60 com adição de 1,5% em peso de mischmetal) por fundição convencional e ZK60-1,5RE tixofundidas com batimento mecânico no estado semissólido. Todas foram laminadas a quente em um laminador simétrico e soldadas por fricção e mistura mecânica. Os métodos de fundição e resfriamento apresentaram materiais isentos de defeitos e com homogeneidade química, além do batimento mecânico proporcionar uma microestrutura com grãos globulares homogêneos. A adição de Mischmetal deu origem a uma microestrutura com granulometria aproximadamente 22% menor. Quando comparado com o método de fundição, a liga fundida com batimento no estado semissólido apresentou uma diminuição no tamanho médio de grão de aproximadamente 26%. A laminação deu origem a uma microestrutura parcialmente recristalizada, com tamanho médio de grãos entre 3 e 4 μm. A rede de intermetálicos foi quebrada, porém, manteve-se contínua para as ligas com adição de Mm. Quanto à resistência mecânica, a liga ZK60 foi superior, devido à menor quantidade e redes intermitentes de intermetálicos, uma vez que tanto para as ligas fundidas quanto para as laminadas, as trincas foram originadas nas regiões de aglomeração de intermetálicos. As ligas com adição de Mm apresentaram melhor estabilidade térmica durante a soldagem e melhor acabamento superficial, sendo possível a soldagem com rotação de 1200 rpm e velocidade de avanço de 400 mm/min enquanto a liga ZK60 só foi possível a soldagem com 200 mm/min. As análises das tensões residuais apresentaram valores e perfis semelhantes e seguem o fluxo de material, bem como a textura dos cordões de solda. Os mapas de microdureza na secção transversal do cordão de solda revelaram maior dureza nas zonas de mistura, e valores ainda maiores e mais homogêneos para liga ZK60, pode-se afirmar que os intermetálicos do tipo MgZn tem maior dureza que os do tipo MgZnRE.
The growing scarcity of renewable energy resources, as well as the continued rise in costs has required in recent decades a dramatic reduction in energy used for transportation freight and passenger, which is increasing daily all over the world. An alternative is to weight reduction with the use of light alloys, this concept the use of magnesium alloys is justified by their low density, about 1/3 lower than that of aluminum. Among the magnesium alloy, the matrix is ZK type that has greater mechanical strength and the addition of rare earth elements (RE) to increase corrosion resistance, working temperature and yield strength due to the formation of thin films and density oxides, and intermetallic of the high melting point and higher hardness. The formation of intermetallic of the MgZn type, which has a low melting point, makes alloys with matrix of the ZK type susceptible to formation of hot crack during the welding, making impossible the use of conventional welding processes, an alternative is the friction stir welding (FSW) that the union is made below the melting point. This work shows the studies the addition of 1.5% wt. of mischmetal (Mm) in the ZK60 alloy and effects of the casting process with mechanical mixing in the semi-solid state. Were produced the alloys: ZK60, ZK60-1.5RE with conventional casting and ZK60-1.5RE Tixo with mechanical mixing in the semi-solid state, all were hot-rolled in a symmetrical laminator and welded with friction stir welding (FSW) process. The methods of casting and cooling gave resulted in materials free of defects and chemical homogeneity, and the mechanical mixing provides homogeneous microstructure with globular grains. The alloy with mischmetal addition had an average grain size of about 22% lower than ZK60 alloy, when compared to the casting method the ZK60- 1.5RE Tixo alloy had an average grain size of about 26% lower than ZK60-1.5RE alloy. The rolling process gave rise to a partially recrystallized microstructure with average grain size of between 3.3 and 4.23 μm, the intermetallic network were broken, however, kept continuous for alloys with Mm addition. As for mechanical strength was higher for ZK60 alloy, due smaller amount and intermittent network of the intermetallic. The alloys with Mm addition had better thermal stability during welding and showed better surface quality, being possible to do a welding with rotation of 1200 rpm and advancing speed of 400 mm/min while the ZK60 alloy only was possible the welding with advancing speed of 200 mm/min. The analyzes of residual stresses had similar values and profiles and follow the flow of material as well as the texture of the weld beads. The micro hardness maps in the cross section of the weld bead showed a higher hardness in the mixing zones, and higher and more homogeneous values for ZK60 alloy, and can thus affirm that the intermetallic MgZn type has higher hardness than the MgZnRE type.

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Ökshei, Jorunn, and Hannah Eriksson. "Certifieringens betydelse för naturvärden i skogen." Thesis, Linnéuniversitetet, Institutionen för skog och träteknik (SOT), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-85925.

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En viktig målsättning i den svenska skogspolitiken är att skogsbruket ska bedrivas på ett hållbart sätt och i Skogsvårdslagen är produktionsmålen och miljömålen jämställda. Skogsägare kan utöver detta åta sig att certifiera sin fastighet, antingen genom FSC eller PEFC. Certifiering är ett marknadsdrivet, frivilligt åtagande och handlar om att ta ett större ansvar för miljö och natur än vad Skogsvårdslagen kräver. Syftet med denna studie är att jämföra förekomst av naturvärden på certifierade fastigheter och icke-certifierade fastigheter genom fältinventering av utvalda kriterier. Kriterierna valdes utifrån mätbara och synliga indikatorer på naturvärden och utifrån faktorer som speglar variationsrikedom, hänsyn, kontinuitet, flora-och faunaobjekt och återväxt. I denna studie har vi arbetat fram en funktionell inventeringsmall i syfte att kartlägga naturvärden på fastighetsnivå. En slutsats från inventeringen var att naturens egna förutsättningar är en viktig faktor för förekomsten av naturvärden i högre grad än om fastigheten är certifierad eller inte.

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Vergara, Mesina Benjamín. "Modelamiento acoplado térmico y de deformación en soldadura por fricción-agitación." Tesis, Universidad de Chile, 2017. http://repositorio.uchile.cl/handle/2250/148355.

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Ingeniero Civil Mecánico
La presente memoria tiene como objetivo el corroborar, reformular y combinar ecuaciones asintóticas para obtener expresiones explícitas útiles para la soldadura por fricción-agitación (FSW). Para ello se crea una base de datos y se rede ne el modelo asintótico asociado a esta, para plantear ecuaciones fundamentales y corroborar las diferentes aproximaciones que las de nen, además de agregarles factores de corrección. La FSW aprovecha el calor generado por el roce entre las placas a soldar y la herramienta giratoria usada, para generar la unión entre los metales. Su ventaja es que se obtienen mejores propiedades mecánicas y por lo mismo, está siendo ampliamente utilizada; pero dado que se estudia por ensayo y error, es necesario que se desarrolle mayor conocimiento teórico sobre ella. Por ello, varios investigadores han desarrollado modelos para representar los fenómenos que gobiernan esta soldadura y en el caso de esta tesis, se utiliza el método de escalamiento adimensional. Se observa que las aproximaciones presentan variaciones menores al 12% por lo que son aceptables, excepto para el caso de Zener-Hollomon en que es necesario estudiar la tasa de deformación usada. Por otro lado, los factores de corrección en general presentan valores menores a 4, lo que se considera satisfactorio para el nivel de aproximación y resultados trabajados. Además, no se puede de finir un solo epsilon para AA5059 y AA7075, por lo que se debe estudiar más materiales, pero sí se concluye que se logran modelar los fenómenos asociados a esta soldadura, con resultados útiles para la ciencia.
Este trabajo ha sido parcialmente financiado por el Gobierno Canadiense a través de la Beca "Emerging Leaders in the Americas Program"

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Bozzi, Sandrine. "Optimisation du procédé FSSW (Friction Stir Spot Welding) pour des assemblages homogènes A1/A1 et hétérogènes A1/Acier." Paris 11, 2009. http://www.theses.fr/2009PA112314.

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Le Friction Stir Spot Welding (FSSW) est un procédé de soudage thermomécanique : un outil constitué d’un épaulement et d’un pion est mis en rotation rapide et pénètre dans les deux tôles superposées à assembler. La chaleur produite par le frottement de l’outil sur les tôles provoque un ramollissement de la matière. La rotation du pion permet alors de malaxer la matière des deux tôles. L’outil se retire ensuite en laissant une empreinte. Le FSSW permet ainsi le soudage de l’aluminium grâce à un malaxage entre les deux tôles. L’écoulement de la matière dans la zone de malaxage a pu être identifié. Il existe précisément deux flux distincts : des remontées externes de la matière et un malaxage interne le long de la paroi du pion. Il en résulte alors l’apparition de stries dans la zone de malaxage, qui correspondent à des films de matière fondue provenant du dessous du pion. D’un point de vue microstructurale, le mécanisme de recristallisation dynamique continue a été identifié, si bien que la zone de malaxage correspond à une zone de petits grains recristallisés d’environ 5µm de diamètre, entrecoupés de stries de grains plus fins d’environ 1µm, et de composition chimique différente. Quant aux propriétés mécaniques, elles sont fortement liées à l’écoulement de matière et à la microstructure qui en résulte, comme le montre notamment les mécanismes de rupture. La rupture à lieu par la propagation de la fissure située à l’extrémité de l’interface entre les deux tôles. Cette fissure se propage généralement en contournant la zone de malaxage qui présente une forte dureté due à l’affinement des grains, en empruntant le chemin marqué par le resserrement des stries. Ainsi, un moyen évident de retarder la rupture est donc d’obtenir une zone de malaxage la plus large possible. Mais il ne s’agit pas du seul facteur pour optimiser la tenue mécanique des points de soudure. L’inclinaison de la fissure à l’extrémité de l’interface est une autre donnée très influente. L’assemblage entre l’aluminium et l’acier, quant à lui, est rendu possible grâce à une accroche, c’est-à-dire à une remontée d’acier dans la tôle d’aluminium. Il y a alors formation de composés intermétalliques à l’interface entre l’accroche d’acier et l’aluminium grâce à un effet thermomécanique. Les précipités intermétalliques qui en résultent au niveau des accroches présentent une taille d’environ 250 nm et une dureté qui diffère fortement selon leur nature, allant jusqu’à 1100 HV. Ces zones intermétalliques deviennent alors des zones très fragiles qui peuvent détériorer le comportement mécanique des soudures. Lorsque ces précipités sont trop nombreux, et que leur microdureté est élevée, la rupture des points de soudure provient de nombreuses fissures qui apparaissent au niveau des zones intermétalliques. Mais ils restent nécessaires, car s’ils sont quasi inexistants, la tenue mécanique est très faible, la rupture ayant lieu par une rapide décohésion entre l’accroche d’acier et l’aluminium. Ainsi, pour une tenue mécanique optimale, une certaine quantité d’intermétalliques est nécessaire, ce qui correspond également à une surface d’accroche plus importante. Dans ce cas, l’accroche étant plus robuste, la rupture a lieu par déchirure de la tôle d’aluminium. L’ensemble des résultats a permis de montrer le fort potentiel du FSSW pour des applications homogènes de l’aluminium ainsi que pour des applications hétérogènes entre l’aluminium et l’acier
Friction Stir Spot Welding (FSSW) is a thermomechanical joining process : a tool constituted by a retaining wall and by a pawn is put in fast rotation and penetrates into both sheet stacked to assembly. The heat produced by the friction of the tool on sheets provokes a softening of the material. The rotation of the pawn allows then to mix the material of both sheets. The tool withdraws then by leaving an imprit. Therefore the FSSW allows the joining of aluminium alloys thanks to a mixing between both sheets. The flow of the material in the stir zone was able to be indentified. There are exactly two different streams : external rises of material and an internal mix along the wall f the pawn. It results the appearance of streaks in the stir zone, which correspond to films of melted material resulting from the bottom of the pawn. From a microstructural point of view, the mechanism of dynamic continous recrystallisation was identified, so that the stir zone corresponds to a zone of small recristallized grains about 5 µm of diameter, interrupted of streak with finer grains about 1 µm, and of different chemical composition. As for the mechanical properties, they are strongly bound to the flow of material and to the microstructure which results from it, as shows it in particular the mechanism of break. The break take place by the distribution of the crack situated at the end of the interface between both sheets. This crack propagates generally by contourning the stir zone, which presents a strong hardness due to the refinement of grains, by taking the way marked by the contraction of sreak. S, an evident means to delay the break is to obtain the widest possible stir zone. But it is not about the only factor to optimize the mechanical strength. The slope of the crack a the end of the interface is another very influential datum. The assembly between aluminium and steel, as for its, is possible thanks to a hhok, that is to say an ascent of steel into the aluminium sheet. There is then formation of intermetallic compounds in the interface between the steel hook and the aluminium, thanks to a thermochemical effect. The intermetallic precipitates present a size about 250 nm, and a hardness which differs strongly according to their nature, until 1100 to HV. These intermetallic areas become the very fragile zones which can damage the welds mechanical behaviour. When these precipitates are on a too important quantity, and when their microhardness is raised, the hook rupture results from numerous cracks. But those intermetallic compounds remain necessary, because if they are almost non-existent, the mechanical strength is very weak : the fracture taking place by a fast separation between steel and aluminium. So, for an optimal mechanical strength, a certain quantity of intermetallic compounds is necessary, what also corresponds to a surface of sticks more important. In that case, hooks being more strong, the fracture takes place by a tear of the aluminium sheet. All the results allowed to show the strong potential of the FSSW for homogeneous applications of aluminium as well as for heterogeneous applications between aluminium and steel

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Kittipanya-ngam, Pichawadee. "Downstream food supply chain (FSC) in manufacturing firms : operating environment, firm's strategy, and configuration." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608839.

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Miyaura, Edson Haruo. "Efeito das tensões residuais sobre a propagação de trincas em juntas soldadas por FSW." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265149.

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Orientador: Renato Pavanello
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Inúmeros trabalhos de pesquisa tem sido feitos em torno de um processo de soldagem por atrito conhecido por FSW, ou Friction Stir Welding. A proposta deste trabalho é determinar o efeito das tensões residuais resultantes de tal processo sobre a propagação de trincas na região próxima à junta soldada. Este efeito é considerado calculando-se fatores de intensidade de tensão residual pelo uso de funções ponderadoras e pelo método de elementos finitos. Técnicas numéricas e equações de taxa de propagação modificadas são empregadas para determinar a vida residual em fadiga de sólidos com trincas que atravessam transversalmente a região da solda. É abordado e aplicado um meio de determinar uma curva de tensão residual longitudinal a partir de uma curva de fatores de intensidade de tensão residual. Finalmente, o ensaio cut compliance é apresentado como uma técnica experimental eficaz na determinação de uma curva de fatores de intensidade de tensão residual. A aplicação de tal método exige o conhecimento prévio ou o cálculo de funções de influência. Demonstra-se que o método de elementos finitos é eficaz na determinação de tais funções
Abstract: Numerous research papers have been published on a process known as friction stir welding or FSW. The purpose of this work is to determine the effect of residual stresses resulting from such process on the propagation of a crack near the weld. This effect is taken into account by calculating residual stress intensity factors using weight functions and finite elements. Numerical techniques and crack propagation rate equations are employed to determine residual fatigue life of solids with cracks that traverse across the weld region. A way to determine a longitudinal residual stress curve from a residual stress intensity factor curve is discussed and applied in this work. Finally, the cut compliance method is presented as an effective experimental technique to determine residual stress intensity factor curves. The application of such method requires calculation of influence functions. It is shown that the finite element method is effective in determining those functions
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica

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Michels, Michel. "Solda topo de placa em liga AA 7050t7451 pelo método friction stir welding (FSW)." Instituto Tecnológico de Aeronáutica, 2013. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=3401.

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O presente trabalho tem como objetivo desenvolver soldagem de junção de topo, no estado sólido, de placas de alumínio 7050-T7451 de espessura 0,625 pol, para aplicação aeronáutica em asas, por meio da técnica Friction Stir Welding - FSW, obtendo-se boas propriedades mecânicas, produzindo peças integrais, desta forma reduzindo peso da aeronave. O processo de FSW foi patenteado, em 1991, pelo The Welding Institute (TWI) da Inglaterra. O processo consiste na união realizada no estado sólido, não ocorrendo fusão dos materiais. A ferramenta é projetada, com uma geometria similar a um pino, tem a função de aquecer e "misturar" as bordas de duas peças que se quer unir. A ferramenta ainda tem um ombro que rotaciona sobre o material, gerando atrito e, consequentemente, gera energia térmica para plastificar o material. No desenvolvimento deste trabalho, foram realizadas as seguintes etapas: revisão bibliográfica do FSW; parâmetros de processo já definidos e realização de ensaios práticos; caracterização das juntas soldadas; ensaios mecânicos. Devido à grande espessura da chapa e usando uma ferramenta existente, a solda foi realizada dos dois lados. Por meio de inspeção visual observou-se que a solda possui bom acabamento superficial, com largura regular na impressão do ombro da ferramenta. Na região de transição entre o nugget e ZTMA fica evidente o fluxo de material entre a superfície e o interior das placas. Observa-se um refino do tamanho de grão e diminuição do tamanho dos precipitados pela análise por microscopia óptica. O gráfico dos valores de microdureza mostra-se coerente com o processo de solda realizada. Por meio de testes de tração constata-se que não houve rompimento dos corpos de prova na região da solda, evidenciando a qualidade da mesma.

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Córdova, Thais Gabriele Zamboni. "Impactos da certificação FSC SLIMF nos meios de vida de grupos de pequenos produtores." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-26072018-134213/.

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As certificações socioambientais, a fim de tornarem-se mais acessíveis a pequenos produtores proporcionam métodos alternativos para obtenção dos selos. O FSC, além da possibilidade de certificação em grupo oferece, desde 2004, o padrão de certificação Small and Slow Intensity Managed Forests (SLIMF). No Brasil, para atender a alta demanda do mercado e manterem-se competitivas, empresas florestais, além de estabelecer contratos de fomento, vêm incentivando e auxiliando pequenos produtores a certificarem-se. Para os pequenos produtores, a certificação pode contribuir com a diversificação dos meios de vida. O presente estudo teve como objetivos: i) caracterizar quais são os fatores que geram mudanças nos meios de vida de grupos de pequenos produtores florestais fomentados certificados; e ii) verificar a influência do tempo de certificação na mudança dos capitais dos meios de vida destes grupos. Para isso foram estudados quatro grupos de produtores florestais fomentados e certificados com FSC SLIMF, e um grupo fomentado, porém não certificado. Estes grupos localizam-se nas regiões brasileiras do extremo sul do estado da Bahia e norte do Espírito Santo, e vale do rio Tibagi, no estado do Paraná. Os grupos foram caracterizados por meio de entrevistas e levantamento bibliográfico. Os impactos da certificação nos meios de vida dos grupos de pequenos produtores florestais foram mensurados por meio questionário baseado em adaptação da abordagem dos Meios de Vida Sustentáveis. Foram propostos cenários da influência da certificação nos meios de vida de cada grupo certificado e interpretadas as interações entre os capitais dos meios de vida. O bom desempenho da certificação foi influenciado pela demanda do mercado por produtos certificados, pela situação prévia do capital social dos grupos de produtores e suas condições socioeconômicas. A certificação FSC SLIMF promoveu mudanças positivas em todos os capitais dos meios de vida, porém em intensidade diferente em cada grupo. Foi unânime a percepção de maior mudança no capital natural. O capital financeiro, principal motivador para participação na certificação, não apresentou o Preço Premium esperado pelos produtores. O tempo de certificação influenciou positivamente os resultados em todos os meios de vida, entretanto o engajamento e a participação dos membros na gestão dos grupos é determinante para o sucesso da certificação. Aspectos como escolaridade e renda influenciaram no interesse em se certificar e na percepção de melhorias.
Socio-environmental certifications, in order to become more accessible to small producers, provide alternative methods of obtaining the acreditation. The FSC, in addition to the possibility of group certification, has offered the Small and Slow Intensity Managed Forests (SLIMF) certification standard since 2004. Brazilians forestry companies, in order to meet the market\'s high demand and to remain competitive, not only have established outgrower schemes, but also have encouraged and assisted small producers to certificate. Certification can contribute to the diversification of smallholders\' livelihoods. The present study had as objectives: i) to characterize the factors that generate changes in groups of certified forest smallholders\' livelihoods; and ii) to verify the influence of time of certification on the change of livelihood assets of these groups. Four groups of FSC SLIMF certified smallholders outgrowers, and a not certified smallholder outgrower group were selected to this study. These groups are located in the Brazilian regions of the extreme south of Bahia and north of Espirito Santo, and the Tibagi river valley in Paraná. The groups were characterized by interviews and bibliographic surveys. The certifications\' impacts on the smallholders\' livelihoods were measured using a questionnaire based on an adaptation of the Sustainable Livelihoods approach. Scenarios on the certification\'s influence on each group\'s livelihoods were developed and the interactions between livelihood capitals were interpreted. The certification\'s positive performance was influenced by the market demand for certified products, the smallholders groups previous situation on the social capital and their socioeconomic conditions. The FSC SLIMF certification promoted positive changes in all livelihoods\' capitals, but at different intensities in each group. The perception of higher change in the natural capital was unanimous. The financial capital, considered to be the main participation motivator in the certification, did not present the Premium Price expected by the producers. Certification time positively influenced outcomes across all livelihoods, however engagement and participation of group members in management is key to successful certification. Aspects such as schooling and income influenced the interest in pursuing certification and perceiving improvements.

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Basso, Vanessa Maria. "Desafios e oportunidades da certificação do manejo florestal pelo sistema FSC no continente americano." Universidade Federal de Viçosa, 2015. http://www.locus.ufv.br/handle/123456789/6777.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
A certificação florestal é uma ferramenta de mercado, voluntária e não governamental que está sendo utilizada como mecanismo de garantia para o “bom manejo florestal”, sob o cumprimento de princípios ambientais, econômicos e sociais. São vários os fatores que levam uma organização florestal a buscar uma certificação, tais como: exigências de mercados, críticas socioambientais da sociedade, requerimentos legais, necessidade de melhoria da imagem institucional, dentre outros. Um dos principais sistemas de certificação florestal reconhecido mundialmente é o FSC – Forest Stewardship Council, atuante desde de 1993. Ao reconhecer que o continente americano é um grande produtor e exportador de produtos florestais no mercado mundial e, também, possui extensas áreas com florestas naturais e plantações florestais, viu-se a necessidade de entender como a certificação florestal vem sendo impulsionada em seus países. Assim, buscou-se com a presente pesquisa analisar as influências, contribuições, oportunidades e desafios da certificação florestal pelo sistema FSC nos principais países com produção florestal no continente. O estudo foi dividido em três capítulos e desenvolvido a partir de metodologias da pesquisa social, em específico a pesquisa descritiva por meio de análise de documentos oficiais. Como resultados, verificou-se que apesar do aumento de certificados de manejo florestal, na última década, o percentual de área certificada ainda é baixo se comparado com a área de florestas nativas e de produção florestal dos países americanos. Os países com maior número de certificados são Estados Unidos, Canadá e Brasil. Entretanto, os fatores que influenciaram cada país foram diferentes. O Canadá apresentou a maior área certificada impulsionados por incentivos e exigências de seu governo e indústrias. Os Estados Unidos apresentaram o maior número de certificados de Unidades de Manejo florestal (UMF), que possivelmente foram impulsionados pelas críticas da sociedade e suas organizações florestais buscaram a certificação como evidência de suas boas práticas socioambientais. Já no Brasil, dois fatores contribuíram para que os empreendimentos florestais buscassem a certificação: as críticas da sociedade e as exigências de mercado, principalmente, da União Europeia. Com relação à certificação de pequenas propriedades têm-se destaque as iniciativas na Guatemala, Honduras e México, que contaram com apoio de seus governos e de ONGs internacionais. Contudo, de forma geral, na maior parte dos países analisados, o mercado interno ainda não requer a certificação florestal, o que acaba por não gerar demanda para que as demais organizações do setor se certifiquem. Quanto aos desvios, verificou-se um menor percentual de não conformidades entre as organizações dos Estados Unidos e do Canadá, o que sinaliza melhor preparo nas atividades de manejo. Nestes países os maiores desvios estavam relacionados às questões ambientais. Já nos demais países da América Latina, independente da escala, os percentuais de não conformidades por organização foram bem maiores e prevaleceram sobre os quesitos trabalhistas, seguidos das questões ambientais. Com relação aos benefícios econômicos, estudando se casos no Brasil, verificou-se que as contribuições da certificação florestal foram baixas. Acredita-se que uma análise aprofundada, em que sejam considerados as contribuições socioambientais indiretas, poderá evidenciar melhor os benefícios econômicos. Por fim, verifica-se como ponto positivo, em todos os casos, é que a adesão à certificação florestal exigiu a implementação de modelos de gestão ambiental e social mais rigorosos que os aplicados anteriormente à decisão da certificação. Um ponto fundamental para que os números de certificados florestais aumentem nos países americanos é a geração de demanda em seus mercados internos. Assim, é importante que o sistema de certificação FSC e as partes envolvidas no processo amplie sua divulgação e imagem do que realmente significa a sua logomarca para os consumidores finais.
Forest certification is a marketing strategy, voluntary and non-governmental that has been used a guarantee mechanism for the "good forest management", according to the environmental, economic and social principles. There are many factors that contribute to a forestry organization to seek for a product certification, such as markets requirement, society environmental criticism, legal requirements and/or necessity to improve the institutional reputation. One of the main globally recognized forest certification system is the FSC - Forest Stewardship Council, founded in 1993. Taking account that American Continent is the greatest producer and exporter of forest products and has extensive areas with natural forests and forest plantations, we notice the necessity to understand how forest certification has been promoted in these countries. Thus, this study aimed to analyze the current influences, contributions, opportunities and challenges of the forest certification by the FSC system in the major forest producer countries located in American Continent. The study was divided in three chapters and was developed utilizing methods of social research, in particularly, the descriptive research using data from official documents. Even though we observed an increment of forest management certificates in the last decade, the percentage of certified area is still low compared with the area of native forests and forest production. United States, Canada and Brazil are the countries with the highest numbers of certificates and the factors that influenced the certification demand among countries were different. Canada has the largest certified area driven by incentives and requirements of its own government and industries. The United States has the highest number of Forest Management Units certificates (UMF), which might be driven by society criticism leading its forestry organizations sought by certification, as evidence of their good social and environmental practices. In Brazil, two mainly factors contributed to the certification of forest organizations: the society criticism and market demands, mainly from the European Union. Regarding to small farms certification, we observed important initiatives in Guatemala, Honduras and Mexico, supporting by their own governments and some international ONGs. Generally, for the most of the countries analyzed, the internal market still does not require forest certification, which ends up not generating demand for other sector organizations to be certificated. In the United States and Canada organization, we observed the lower percentage of non-compliances between organizations indicating the better preparation of the management activities. In these countries, the largest deviations were related to environmental questions. In the Latin American countries, the percentage of non-compliance by the organization was bigger and related to labor questions, followed by environmental issues. Regarding to economic benefits, studying specific cases in Brazil, it was found that the contributions of forest certification were low. We believe that a detailed analysis, considering the indirect social and environmental contributions of certification should be considered and possibly could demonstrate the economic benefits to the society. Finally, as a positive result in all cases, we observed that the forest certification induced to an implementation of more rigorous environmental management and social models compared to the utilized before the certification process. A fundamental point for increasing the forest certificate numbers in American countries is the generation of demand in their domestic markets. In this way, it is important that the all certification FSC system involved in this process expanding its outreach and image of the final product reaching the final consumers.

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Allred, Jacob D. "An Investigation into the Mechanisms of Formation of the Hard Zone in FSW X65." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3806.

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Friction stir welding (FSW) of HSLA steel commonly produces a hard zone (HZ) on the advancing side (AS) of the weld. Despite its detrimental effects on weld toughness, the mechanisms of its formation have not been thoroughly investigated and are not well understood. This paper investigates the various mechanisms in FSW believed to affect the weld HZ, namely: strain, strain-rate, peak temperature and cooling rate. Gleeble tests indicate that strain and strain rate have negligible effects on weld HZ with cooling rate and peak temperature as dominant effects. Jominy tests resulted in cooling rate having 270% greater influence than peak temperature on the formation of lath ferrite microstructures similar to what is observed in the HZ of FSW X65. Comparing weld HZ microstructures to Jominy tests, it is estimated that cooling rates on the AS of the weld are at least 150°C/s higher than the retreating side. Reducing the cooling rate on the AS will likely lead to an improved microstructure at the weld HZ.

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Oliveira, Jaqueline José Silva. "O PADRÃO DE CERTIFICAÇÃO DO FSC (FOREST STEWARDSHIP COUNCIL) PARA O MANEJO DE PLANTAÇÕES DE TECA NO BRASIL Na Perspectiva da Racionalidade Ambiental e do Capitalismo Natural." Pontifícia Universidade Católica de Goiás, 2010. http://localhost:8080/tede/handle/tede/2781.

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The environmental problem is characterized essentially by a frenetic search to change the current economic model to a new stage of capitalism, called Natural Capitalism. This presents four principles as indispensable ways of maintaining the Earth and its species, without the naïve vision of non-development, limits to growth and the don quixotic cries to save the Earth from the obvious high global temperatures which provoke climate change. These changes are caused by polluting activities, especially those which increase the greenhouse effect, and by the lack of energetic measures to preserve the environment. A less romantic view of the proposals of Natural Capitalism will be discussed in this study which could lead to the reappropriation of nature, through the sustainable development discourse, which has attracted international agreements to guarantee sustainability (highlighting the Quioto Protocol and CON 15 in Copenhagen). This dissertation, for reasons which will become apparent, focuses on the question of environmental sustainability, based on the tripod (Triple Bottom Line) including economic, social and environmental dimensions. A significant issue that must be observed is the fact that in order to effectively guarantee a permanent adaptation of the new model of development being proposed, it is not sufficient that business leaders assimilate the concept of sustainability and produce without degrading the environment. Consumer awareness must be heightened in order to move towards an ethical market. It is up the consumer to get to know the economic, environmental and social impact of products which s/he rewards by purchase. The identification of products coming from politically correct companies will be carried out through stamps or certification, especially the green stamp, from the Forest Stewardship Council (FSC). It aims to justify the guarantee and differentiation which the FSC offers to the investor, in this case, though the plantation Teak on Brazilian land, as compared to different kinds of forest certification around the world and in Brazil.
A presente dissertação objetiva, valendo-se de subsídios multidisciplinares, analisar e demonstrar a importância do Padrão de Certificação do FSC (Forest Stewardship Council) para o manejo de plantações de teca no Brasil, bem como confrontar as questões teóricojurídicas controvertidas que deverão alcançar o âmbito diferenciado deste programa de certificação florestal, comparado aos demais sistemas existentes. O trabalho orienta-se através dos métodos hipotético-dedutivo e comparativo, apropriados ao objeto de estudo, para sanar as questões levantadas e de técnicas de investigação seguras, notadamente histórica e a monográfica. Para tanto, fez-se uso de referenciais teóricos obtidos pelas pesquisas bibliográficas e em websites, dos esquemas de certificação florestal. No transcorrer do desenvolvimento deste trabalho, destaca-se a problemática ambiental, que se caracteriza, primordialmente, pela frenética busca de mudança do modelo econômico atual para uma nova era do capitalismo: o Capitalismo Natural (Natural Capitalism). Este apresenta quatro princípios como via imprescindível na manutenção do globo e suas espécies, sem a ingênua visão (do não-desenvolvimento e dos limites ao crescimento), ofuscada pela ideologia salvacionista do planeta em relação às evidentes elevações da temperatura média global, que ocasionaram alteração climática, provocada pelas atividades poluidoras, sobretudo, as que aumentaram o efeito estufa, somadas à falta de medidas enérgicas, com o propósito de preservação ambiental. A óptica menos romântica da proposta fundamentada nos quatro princípios do capitalismo natural, que serão citados ao longo deste estudo, desemboca na reapropriação da natureza, através do discurso de desenvolvimento sustentável, em que as dificuldades em resguardar o planeta atraíram acordos internacionais (destacando o Protocolo de Quioto e a Convenção 15, em Copenhague), para garantir a sustentabilidade. A abordagem deste tema, por razões que se tornarão evidentes, está voltada para a questão ambiental, no conceito de sustentabilidade, fundamentado no tripé (Triple Bottom Line) que abrange o econômico, o social e o ambiental. Um ponto importante a ser observado consiste no fato de que a garantia de uma efetiva adaptação ao novo modelo de desenvolvimento proposto não se encontra apenas no processo de as lideranças empresariais assimilarem o conceito de sustentabilidade e produzirem sem degradar o meio ambiente, mas, especialmente, na conscientização do consumidor, o qual norteará um mercado ético. Cabe a ele saber qual é o impacto econômico, ambiental e social, que geram os produtos que premia com a sua compra. A identificação dos produtos de empresas politicamente corretas será feita através de selos ou certificações, no caso específico, do selo verde - FSC (Forest Stewardship Council), almejado pelos empreendedores madeireiros, em particular, os de plantio da tectona grandis no Brasil.

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