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ZHU, YINGSONG, AKIKO TSUCHIDA, AKIHITO YAMAMOTO, KEIKO FURUKAWA, ORIE TAJIMA, NORIYO TOKUDA, SHINICHI AIZAWA, TAKESHI URANO, KENJI KADOMATSU, and KOICHI FURUKAWA. "EXPRESSION AND ROLES OF A XENOPUS HEAD-FORMING GENE HOMOLOGUE IN HUMAN CANCER CELL LINES." Nagoya University School of Medicine, 2008. http://hdl.handle.net/2237/10543.
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Тараненко, Михайло Григорович. "Трубний агрегат з модернізацією формуючої головки." Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/42001.
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Об’єкт розробки – модернізований екструдер типу ЧП 125х32. Предмет розробки – формуюча головка екструдера ЧП 125х32. Метою дипломної роботи «Трубний агрегат з модернізацією формуючої головки» є розробка модернізованого екструдера для виробництва труб із ПВХ, зокрема його формуючої головки. Модернізація направлена на покращення якості перемішування розплаву полімеру, що несе за собою покращення якості виробу в цілому. У дипломній роботі був спроектований червячний прес нової конструкції ЧП 125х32. Виконані всі інженерні розрахунки, у тому числі теплові розрахунки і розрахунки на міцність ряду вузлів і деталей.The object of development is an upgraded extruder of the state of emergency 125x32. The subject of development - the forming head of the extruder PE 125x32. The purpose of the thesis "Pipe unit with the modernization of the forming head" is to develop an upgraded extruder for the production of PVC pipes, in particular its forming head. The modernization is aimed at improving the mixing quality of the polymer melt, which leads to an improvement in the quality of the product as a whole. In the thesis the worm press of a new design of state of emergency 125х32 was designed. All engineering calculations are performed, including thermal calculations and calculations for the strength of a number of components and parts.
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Романченко, Денис Сергійович. "Лінія для виробництва рукавної плівки з модернізацією головки." Master's thesis, КПІ ім. Ігоря Сікорського, 2021. https://ela.kpi.ua/handle/123456789/45783.
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В роботі приведені параметричні розрахунки екструдера і головки, розрахунки на міцність складальних одиниць і деталей екструдера, розрахунок техніко-економічних показників, рекомендації щодо монтажу та експлуатації лінії, рівень стандартизації та уніфікації, додаток з технологічним процесом виготовлення деталі фланець і додаток по автоматизації черв'ячного екструдера.
Модернізація голівки виконана за рахунок зміни глибини та кількості поздовжніх пазів розмір яких зменшується пропорційно і дискретно з кожним наступним сегментним рядом так, що крок між сегментами дорівнюватиме зовнішньому діаметру гвинтової лінії черв'яка, та 1/5 зовнішнього діаметра гвинтової лінії. Кількість повздовжніх пазів відповідатиме кількості сегментних виступів та є однаковою в кожному сегментному ряді.The paper presents parametric calculations of the extruder and head, calculations for the strength of assembly units and parts of the extruder, calculation of technical and economic indicators, recommendations for installation and operation of the line, level of standardization and unification, application with technological process extruder. Modernization of the head is performed by changing the depth and number of longitudinal grooves, the size of which decreases proportionally and discretely with each subsequent segment row so that the step between segments is equal to the outer diameter of the helical helical line and 1/5 of the outer diameter of the helical line. The number of longitudinal grooves will correspond to the number of segment protrusions and is the same in each segment row.
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Underhill, Richard P. "The spray forming of Ni based superalloys." Thesis, University of Oxford, 1995. http://ora.ox.ac.uk/objects/uuid:a26505d4-90cf-41ff-86e9-fbf903c9a87f.
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The main aim has been to investigate the effect of process parameters on the spray forming of UDIMET 720 and in particular to understand the mechanism of grain size evolution in the deposit using a combination of experimental and computer modelling techniques. Samples of two spray formed Ni superalloys, MAR-M-002 and UDIMET 720, have been re-heated into the solid/liquid region and the fully solid region just below the solidus temperature for a series of times to try and reproduce the situation of grain growth in a spray formed deposit. Grain growth in the solid/liquid region follows the equation: d3=d03 +Kt, where d is the grain size, d0 is the initial grain size, K is the coarsening rate constant and t is the time. Coarsening rate constants have been determined for temperatures in the solid/liquid region and they increase with increasing temperature/decreasing solid fraction. Existing spray forming equipment for Al alloys has been modified to manufacture UDIMET 720 deposits. Process conditions were monitored continually during spray forming, in particular the temperature of the deposit by embedded thermocouples and infra red thermal imaging of the deposit top surface. Above a deposit temperature of ≈1250°C the microstructure consists of equiaxed fine grains (20μm-35μm) and the porosity is low (<1%). Below this deposit temperature the microstructure consists of droplet "splats" and the porosity is higher (2-4%). The measure grain size increases with increasing deposit temperature and solidification time and agrees reasonably well with the predicted grain size using the above equation. A commercial finite difference based fluid dynamics software program, FLUENT, has been used to model the 2-dimensional dynamic and thermal behaviour of UDIMET 720 droplets during gas atomisation and spray forming. The effect of atomising gas pressure, spray distance and melt mass flow rate on the equilibrated droplet spray temperature has been examined and shows similar variations with process parameters as the measured maximum deposit temperature. The predicted spray temperature at the substrate is always higher than the measured maximum deposit temperatures under all conditions, and increases with (i) decreasing gas pressure, (ii) decreasing spray distance and (iii) increasing MFR. Mean droplet temperatures and velocities are strongly dependent on droplet size, the mean droplet temperature decreases and mean droplet axial velocities increases with decreasing droplet size.
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Haidemenopoulos, Gregory N. "Heat flow and material degradation during laser metal forming." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/14898.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering and Dept. of Materials Science and Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING
Bibliography: leaves 144-146.
by Gregory N. Haidemenopoulos.
M.S.
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McCarthy, Robert W. "Thermomechanical forming of steel plates using laser line heat." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15261.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 107-108.
by Robert W. McCarthy III.
M.S.
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Shimizu, Hideki. "A heating process algorithm for metal forming by a moving heat source." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10526.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997, and Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1997.Includes bibliographical references (p. 229-236).
by Hideki Shimizu.
M.S.
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Steffenburg-Nordenström, Joachim. "Process chain simulation of forming, welding and heat treatment of Alloy 718." Licentiate thesis, Högskolan Väst, Forskningsmiljön produktionsteknik(PTW), 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:hv:diva-10917.
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Manufacturing of aero engine components requires attention to residual stress and final shape of the product in order to meet high quality product standards.This sets very high demands on involved manufacturing steps to meet design requirements. Simulation of manufacturing processes can therefore be animportant tool to contribute to quality assurance.The focus in this work is on simulation of a manufacturing process chain comprising of sheet metal forming, welding and a stress relief heat treatment.Simulation of sheet metal forming can be used to design a forming tool design that accounts for the material behaviour, e.g. spring back, and avoid problems such as wrinkling, thinning and cracking. Moreover, the simulation can also show how the material is stretched and work hardened. The residual stresses after forming may be of local character or global depending on the shape that is formed. However, the heat affected zone due to welding is located near the weld.The weld also causes large residual stresses with the major component along the weld. It is found that the magnitude of the residual stresses after welding is affected by remaining stresses from the previous sheet metal forming. The final stress relieve treatment will relax these residual stresses caused by e.g. forming and welding. However, this causes additional deformations.The main focus of this study is on how a manufacturing process step affects the subsequent step when manufacturing a component of the nickel-based super alloy 718. The chosen route and geometry is a simplified leading edge of an exhaust case guide vane. The simulations were validated versus experiments. The computed deformations were compared with measurements after each manufacturing step. The overall agreement between experiments and measurement was good. However, not sufficiently accurate considering the required tolerance of the component. It was found from simulations that the residual stresses after each process affects the subsequent step. After a complete manufacturing process chain which ends with a stress relief heat treatment the residual stresses were not negligible. VIII Special experiments were performed for studying the stress relief in order to understand how the stresses evolve through the heat treatment cycle during relaxation. It was found that the stresses were reduced already during the beginning of the heating up sequence due to decreasing Young´s modulus and yield stress with increasing temperature. Relaxation due to creep starts when a certain temperature was reached which gave a permanent stress relief.
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Namjoshi, Shanatanu Ashok. "Reaction synthesis of dynamically-densified Ti-based intermetallic and ceramic forming powders." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/19572.
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Perna, Nicholas K. "Effects of Nasalance on the Acoustics of the Tenor Passaggio and Head Voice." Scholarly Repository, 2008. http://scholarlyrepository.miami.edu/oa_dissertations/88.
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PERNA, NICHOLAS (D.M.A., Vocal Pedagogy and Performance) Effects of Nasalance on the Acoustical Properties of the (May 2008) Tenor Passaggio and Head Voice Abstract of a doctoral essay at the University of Miami. Doctoral essay supervised by Professor David Alt and Professor Rachel L. Lebon. No. of pages in text. (73) This study aims to measure the effect that nasality has on the acoustical properties of the tenor passaggio and head voice. Not to be confused with forward resonance, nasality here will be defined as nasalance, the reading of a Nasometer, or the percentage of nasal and oral airflow during phonation. A previous study by Peer Birch et. al. has shown that professional tenors used higher percentages of nasalance through their passaggio. They hypothesized that tenors used nasalance to make slight timbral adjustments as they ascended through passaggio. Other well respected authors including Richard Miller and William McIver have claimed that teaching registration issues is the most important component of training young tenors. It seemed logical to measure the acoustic effects of nasalance on the tenor passaggio and head voice. Eight professional operatic tenors participated as subjects performing numerous vocal exercises that demonstrated various registration events. These examples were recorded and analyzed using a Nasometer and Voce Vista Pro Software. Tenors did generally show an increase of nasalance during an ascending B-flat major scale on the vowels [i] and [u]. Perhaps the most revealing result was that six of seven tenors showed at least a 5-10% increase in nasalance on the note after their primary register transition on the vowel of [a]. It is suggested that this phenomenon receive further empirical scrutiny, because, if true, pedagogues could use nasalance as a tool for helping a young tenor ascend through his passaggio.
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Sarikaya, Onur Turgay. "Analysis Of Heat Treatment Effect On Springback In V-bending." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610182/index.pdf.
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Aluminum based alloys have wide area of usage in automotive and defense industry and bending processes are frequently applied during production. One of the most important design criteria of bending processes is springback, which can be basically defined as elastic recovery of the part during unloading. To overcome this problem, heat treatment is generally applied to the workpiece material to refine tensile properties.
In this study, the effect of heat treatment on springback characteristics of aluminum studied both numerically by using finite element analysis and experimentally. For this purpose, two different materials are selected and various heat treatment procedures are considered. The aluminum sheets having thickness of 1.6 mm, 2 mm and 2.5 mm are bent to 60˚
, 90&
#730
and 120&
#730
. The von Mises stress distributions, plastic strain values and punch load values and comparison of the numerical and experimental results are also given.
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Tinoco, José. "On the Spray Forming of Metals, the Formation of Porosity and the Heat Evolution during Solidification." Doctoral thesis, KTH, Casting of Metals, 2003. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3636.
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This thesis deals with the heat evolution duringsolidification and its relation to the formation of porosity.It intends to improve the current understanding of theformation of porosity in cast materials with special interestin nodular cast iron and the spray forming process. Twodifferent systems, a Fe-based alloy, Cast iron, and a Ni-basedalloy, Inconel 625, are examined. The effect on the heatevolution of the morphology and the processing parameters inspray forming are treated.
An evaluation of the microstructural features, segregationbehavior and physical properties such as latent heat of fusionis performed byusing thermal analysis under cooling ratesranging from 0.1 to 104 K/s. In order to achieve this amodified differential thermal analysis (DTA) equipment, amirror furnace and levitation casting are used. Results arepresented in terms of the fraction of solidified, the coolingrate and the microstructure observed. The measured latent heatof fusion is not constant throughout the solidificationprocess. Variations in morphology and cooling rate affect therelease of the latent heat.
A thermodynamic model is used to describe the experimentalobservations and to explain the formation of pores in nodularcast iron by taking into consideration the formation of latticedefects during the liquid/solid transformation. In this casethe formation of porosity is regarded as a consequence ofchanges in the volume fraction ratio graphite/ during thesolidification process.
A numerical model of the spray forming process is developedby means of CFD modelling and compared with experimentalmeasurements performed in an industrial facility. Stagnationpressure measurements provided information about the gas flowvelocity and an analysis of the overspray powder providedinformation about the particle thermal history. Evaluation ofthe deposit was also performed. It is observed that the processconditions in spray forming promote non-equilibriumsolidification even though solidification at the deposit occursat a lower rate. In this case the porosity formed near theinterface substrate/deposit depends largely on the substratetemperature. The presence of certain reactive elements, such astitanium, affects the porosity levels in the rest of thedeposit.
Keywords:Thermal Analysis, Nodular Cast Iron, Inconel625, CFD, Flow Assesment, Multiphase Flow, Spray Deposition,Microporosity, Superalloys
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Liu, Weijie. "Advanced modelling for sheet metal forming under high temperature." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0019/document.
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L’objectif de cette thèse est de proposer deux approches complémentaires de modélisation et de simulation numériques des procédés de mise en forme de structures minces. La première est une approche inverse multi-pas, délibérément simplifiée, pour simuler et "optimiser" rapidement et à moindre coût des procédés d’emboutissage de tôles minces, tout en maintenant une bonne précision dans le calcul des contraintes. Un solveur statique implicite est développé en introduisant plusieurs configurations intermédiaires construites efficacement en utilisant une technique de programmation quadratique avec projection. La deuxième approche, de nature incrémentale, repose sur (i) une formulation d’équations de bilan et d’équations de comportement multi-physiques fortement couplés formulées dans le cadre des milieux micromorphes ; (ii) une discrétisation spatiale par EF et temporelle par DF avec un solveur global dynamique explicite et une intégration locale itérative implicite. Une attention particulière est accordée aux aspects thermiques avec l’introduction d’une microtempérature et ses premiers gradients conduisant à l’obtention de deux équations thermiques fortement couplées généralisant de nombreux modèles non locaux proposés dans la littérature. L'approche inverse multi-pas a été implémentée dans le code maison KMAS et l’approche incrémentale non locale a été implémentée dans ABAQUS/Explicit. Des études paramétriques sont menées et des validations sur des exemples simples et sur des procédés d’emboutissage sont réaliséesThe aim of this thesis is to propose two complementary approaches for modeling and numerical simulations of thin sheet metal forming processes. The first one is a deliberately simplified multi-step inverse approach to simulate and "optimize" rapidly and inexpensively thin-sheet stamping processes while maintaining good accuracy in the stress calculation. An implicit static solver is developed by introducing several efficiently constructed intermediate configurations using a quadratic programming technique with projection. The second approach, which is of an incremental nature, is based on (i) a formulation of equilibrium equations and strongly coupled multiphysical behavior equations formulated in the context of micromorphic continua; (ii) spatial discretization by FEM and time discretization by FD with an explicit dynamic global solver and implicit iterative local integration scheme. Particular attention is paid to the nonlocal thermal aspects with the introduction of a micro-temperature and its first gradients leading to two strongly coupled thermal equations generalizing several thermal nonlocal models proposed in the literature. The multi-step inverse approach was implemented in the KMAS in house code while the nonlocal incremental approach was implemented in ABAQUS/Explicit. Parametric studies are performed and validations are carried out on simple examples and on deep drawing processes
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Elfakir, Omer. "Studies on the solution heat treatment, forming and in-die quenching process in the production of lightweight alloy components." Thesis, Imperial College London, 2015. http://hdl.handle.net/10044/1/44976.
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A novel necking prediction model was developed and verified that could be utilised in finite element (FE) simulations for optimisation of high temperature forming processes parameters, such that a successful component could be formed. The temperature-dependent time-based model combines viscoplastic equations, the Hosford yield criterion and the Marciniak and Kuczynski formulation, and is able to capture the effects of varying temperature, strain rate and strain path on the formability of a material. The results of high temperature uniaxial tension tests and isothermal formability tests on the aluminium alloy AA6082 were used for calibration, although the developed model could be similarly calibrated for alternative aluminium alloys. The capability of the model, which could also be run independently, was demonstrated by applying it in a simulation of the solution Heat treatment, Forming and in-die Quenching (HFQ) process for a complex-shaped stiffener component in the commercial FE software PAM-STAMP. The component depth at which severe necking would occur was successfully predicted, and was in agreement with the results of the experimental HFQ trials. The model was subsequently used for the blank shape optimisation of a door inner panel component; the final optimised blank shape was formed experimentally, with the resulting component being free of any cracks and incidences of necking. By decoupling the necking prediction model from the process simulations, significant savings in computational time could be made by selecting only the critical regions in the component where the model would be run. Additionally, the computation could be spread across multiple work stations simultaneously to improve the efficiency of the calculations. The adopted simulation methodology could be expanded further by having multiple independent models that cover other aspects of a forming process such as friction and microstructural evolution.
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Brougham, Rose Marie. "Mother, do you hear me? Daughters forming subjectivities in Spanish American poetry (Olga Orozco, Argentina, Rosario Ferre, Puerto Rico, Maria Negroni, Gloria Gervitz, Mexico)." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3207749.
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Bastos, Silvio Cesar. "Efeito do aquecimento por indução eletromagnetica de tubos sem costura utilizados em motores a diesel." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264397.
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Orientador: Sergio Tonini ButtonDissertação (mestrado profissional) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
Made available in DSpace on 2018-08-14T09:44:38Z (GMT). No. of bitstreams: 1 Bastos_SilvioCesar_M.pdf: 4555280 bytes, checksum: 806976ee18b42ffb327e7bb279b89f96 (MD5) Previous issue date: 2009
Resumo: Este trabalho apresenta um estudo sobre o efeito dos processos de recalque a frio e aquecimento por indução eletromagnética sobre as características da microestrutura e dureza do material de tubo de aço sem costura que é utilizado no transporte de fluxo de combustível em sistema de injeção de alta pressão. Por conduzir combustível, a característica de vedação é crítica para as interfaces de montagem destes tubos. Esta interface tem perfil cônico gerado pelo processo de recalque. A microestrutura obtida na região de vedação pode influenciar na dureza do material devido à conformação plástica ocasionada durante processo de recalque de perfil. Os valores de microdureza observados na região de recalque tendem a estar acima da dureza encontrada no material antes da conformação. Este acréscimo de dureza pode influenciar na vedação ocasionando vazamentos, caso o perfil cônico não tenha acomodação uniforme com o perfil da contra-peça, sendo esta o ""rail"" de distribuição ou a bomba de alta pressão de combustível. O processo de aquecimento por indução pode em condições controladas proporcionar alteração da microestrutura e dureza do material, conforme aquecimento e resfriamento desejados.
Abstract: This paper presents a study about the effect of cold upsetting and electromagnetic induction heating on microstructure and hardness characteristics of steel seamles pipe. This pipe studied is applied in fuel flow transport of high pressure fuel system. As fuel is transported the pipe sealing characteristic is critical on assembly interfaces of this pipe. This interface has conic profile produced at upsetting process. The hardness values observed on cold upsetting pipe has a trend to be higher than raw material. There microstructure changed can cause leakage if sealing contact area between conic profile of components has not accommodation enough, being high pressure pump or "rail". The hardness increase can reduce this sealing contact reducing deformation after tight-fitting. The induction heating process under controlled conditions can furnish change of microstructure and hardness material suitable for leak-tightness.
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
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Stieve, Dale Edward M. "Protein preservation and rumen degradability of ensiled forage, previously treated with microwave or steam heat, formic acid, or anhydrous ammonia." Thesis, This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10312009-020048/.
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Siqueira, Gonçalo. "Caracterização microestrutural, mecânica e tratamento térmico da liga AA-6082 obtida pelo processo de conformação por spray." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-16012013-093254/.
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O processo de conformação por spray é interessante devido à capacidade de conjugar, em apenas uma etapa do processo, a vantagem da técnica de solidificação rápida combinada com alta produtividade dos processos de fundição convencional. Este processo permite a obtenção de materiais livre de macrossegregações, livre de porosidades e com microestrutura refinada. A evolução recente das pesquisas está levando ao desenvolvimento de novas ligas e os resultados têm sido interessantes. O processo de solidificação rápida inerente da conformação por spray permite a produção de ligas com composições diferentes das obtidas pela fundição convencional. O objetivo deste trabalho foi o de caracterizar mecanicamente uma liga de alumínio AA-6082 conformada por spray. Os resultados de testes de dureza Vickers são apresentados para seções de um preformado em relação a sua altura (em um arranjo tridimensional). O material foi avaliado na condição como conformado por spray e após tratamento térmico de solubilização a 525 ºC por 1 h, seguido por envelhecimento a 125 ºC por períodos distintos de 1 h, 10 h, 100 h e 500 h. É mostrado que o a liga AA 6082 conformada por spray mostra uma boa estabilidade térmica em relação a variação da dureza durante o envelhecimento.The spray forming technology combines in a single step the advantages of the rapid solidification techniques and high the productivity of the conventional casting processes, allowing obtention of preforms with a refined microstructure, almost without porosity and macrosegregation free. The development and research efforts are leading to interesting alloys and materials production. The rapid solidification processes inherent to the spray forming allow the production of alloys with different compositions from those obtained by conventional ingot processes. The aim of this work was to carry out mechanical properties characterization of a spray formed AA-6082 alloy. The hardness results are presented in different sections related to the height of the spray formed preform (in a three-dimensional arrangement). The material was evaluated in the as sprayed condition and after heat treatment of solution at 525 ºC for 1 h, and aging for 1 h, 10 h, 100 h and 500 h periods. It was shown that the spray formed AA-6082 aluminum alloy is very stable regarding hardness variation during aging.
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Agouti, Siham. "Étude de l'origine de défauts détectés dans des pièces en alliage d'aluminium de la série 7XXX destinées à l'industrie aéronautique." Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00802983.
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Les travaux de cette thèse s'insèrent dans le cadre de l'étude de défauts détectés par contrôle ultrason dans des pièces forgées en alliage d'aluminium destinées à l'industrie aéronautique.Cette étude a été menée sur deux pièces produites par Aubert&Duval en alliage d'aluminium 7050 fourni par Constellium. Ces pièces ont été sélectionnées sur base d'une étude statistique de l'occurrence des défauts sur cinq années de production industrielle. L'une présente un taux de rebut important du fait de ces défauts, l'autre un taux de rebut quasiment nul, bien qu'elles soient produites avec le même matériau.L'étude de l'origine des défauts a été construite autour de deux axes de recherche:* Axe thermomécanique : formation des défauts pendant la mise en forme par endommagement ductile à chaud.* Axe matériau : caractérisation des défauts préexistants dans le matériau après son élaboration et non refermés pendant la mise en forme.L'axe thermomécanique est basé sur la simulation numérique des gammes de mise en forme des pièces industrielles à l'aide du logiciel Forge® 2009. Le deuxième axe est articulé autour de la caractérisation de l'état de porosité dans un matériau modèle présentant une teneur en hydrogène élevée induisant un taux de porosité plus important que le matériau sain utilisé industriellement. De petits lopins de ce matériau modèle ont été soumis à une campagne de compression alternée simulant le forgeage industriel. La campagne de compression a été conçue par simulation numérique afin de reproduire les conditions thermomécaniques industrielles. Deux techniques de caractérisation complémentaires ont été mises en œuvre pour suivre l'évolution de la porosité : détection indirecte par contrôle ultrason à haute résolution spatiale et observations directes par microscopie électronique à balayage. Une méthode d'analyse quantitative des signaux ultrasonores a été mise au point pour ce travail.La comparaison par simulation numérique du procédé de matriçage des deux pièces industrielles étudiées a permis d'écarter l'hypothèse de la création des défauts par endommagement ductile à chaud. Lors du matriçage, la matière est soumise à des chargements globalement compressifs, et le risque d'endommagement est par conséquent très faible. De plus, comme observé lors de la caractérisation des défauts industriels, les défauts présentent un fond lisse, similaire au fond lisse observé sur les rares porosités présentes dans le matériau industriel à l'état brut d'élaboration. Le même type de fond lisse caractérise également les porosités présentes dans le matériau modèle. Cette observation favorise l'hypothèse de défauts provenant d'un défaut préexistant dans le matériau initial (en l'occurrence à partir d'une porosité). Cette hypothèse est par ailleurs cohérente avec le comportement des porosités lors de la simulation du forgeage sur petits lopins du matériau modèle.Les résultats de cette étude montrent en effet que les porosités ont tendance à s'aplatir et à se refermer pendant la déformation plastique à chaud, sans forcément cicatriser. Les faciès de rupture d'échantillons soumis à de fortes déformations cumulées et ne donnant plus de réponse ultrasonore significative continuent en effet de présenter de petites plages à fond lisse qui témoignent d'une cicatrisation incomplète. Le traitement thermique semble en outre favoriser la réouverture des porosités non cicatrisées (zones lisses) pendant la déformation et leur élargissement (zones ductiles).
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Baumard, Théo. "Modelling the influence of infrared preheating and temperature uniformity in forming of powder-impregnated thermoplastic composites Experimental characterization and modeling of the temperature and rate-dependent shear behaviour of powder-impregnated glass fiber/PA66 woven semipregs." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2019. http://www.theses.fr/2019EMAC0010.
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Le thermoformage non-isotherme de composites thermoplastiques, qui consiste à chauffer une préforme consolidée à une température supérieure à la fusion de la matrice avant de la transférer dans une presse d’estampage, est un procédé bien adapté à la production grande série de pièces structurelles pour l’industrie automobile (avec des temps de cycle < 1 min). L’utilisation d’outils numériques pour prédire l’apparition de défauts en fonction des paramètres procédés utilisés est d’un grand intérêt pour éviter l’emploi de procédures d’optimisation expérimentales couteuses de type essais/erreur. Ces travaux de thèse ont porté sur le développement d’une simulation de la mise en forme de composites poudrés PA66/verre, incluant la modélisation explicite de l’étape de préchauffage infrarouge, afin d’étudier l’effet de l’homogénéité du champ de température sur la présence de défauts de forme. Les propriétés thermophysiques et optiques du matériau ont été caractérisées expérimentalement à deux niveaux de consolidation. La structure du matériau non consolidé conduit à un chauffage moins uniforme, comparé à une préforme préconsolidée. Un modèle éléments finis, basé sur la méthode des radiosités pour la prise en compte des transferts radiatifs a été utilisé pour simuler l’étape de préchauffage ; la démarche a été validée par comparaison avec des essais menés sur un pilote de four infrarouge. L’effet de l’affaissement de la préforme sur la distribution de température a été évalué numériquement, et une procédure d’optimisation pour déterminer les paramètres du four en fonction d’un champ de température requis a été présentée. Le comportement mécanique du composite tissé a été modélisé à l’échelle macroscopique par une loi hypoélastique, implémentée dans Abaqus/Explicit. Les paramètres du modèle ont été déterminés à l’aide d’essais en traction et cisaillement en fonction de la température et de la vitesse de sollicitation. Des simulations non-isothermes de la mise en forme de pièces hémisphériques ont été réalisées, et montrent un bon accord avec les données expérimentales obtenues à l’aide d’un pilote de formage à l’échelle laboratoireNon-isothermal thermoforming of thermoplastic composites, in which a preconsolidated blank is heated above the melting temperature of the matrix before being formed in a press, is a process well adapted to the high production rates of automotive structural parts, allowing for cycle times < 1 min. Numerical tools to predict the apparition of manufacturing-induced defects based on the process parameters used are of an obvious industrial interest to avoid relying on a cost and time intensive trial-and-error approach. This thesis focused on the development of a comprehensive simulation of the forming of powder-impregnated PA66/glass composites, modelling explicitly the infrared preheating step to investigate the effect of temperature homogeneity on shape defects. The thermophysical and optical properties of the material were characterized experimentally at two levels of consolidation, and as a function of temperature when relevant. The structure of the non-consolidated material leads to a less uniform heating, compared to preconsolidated blanks. A finite element model based on the radiosity method to compute the radiative heat transfer was used to simulate the preheating step; this approach was validated against experimental results from a custom-built infrared oven. The model has been used to investigate the effect of blank sag on temperature distribution, and an optimization method to determine the oven parameters based on a desired temperature field has been presented. The mechanical behaviour of the woven composite during forming was modelled with a hypoelastic continuum approach, implemented in Abaqus/Explicit. The model parameters were determined from experimental tensile tests and in-plane shear tests at various temperatures and shear rates. Non-isothermal simulations of the forming of hemispherical parts were conducted, using the temperature field predicted from the preheating simulation as an input, and showed good agreement with that observed on parts formed on a lab-scale thermoforming setup
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Erdiller, Emrah Salim. "Investigation Of Solidification And Crystallization Of Iron Based Bulk Amorphous Alloys." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/1096585/index.pdf.
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The aim of this study is to form a theoretical model for simulation of glass forming ability of Fe �
Based bulk amorphous alloys, to synthesize Fe &
#65533
based multicomponent glassy alloys by using the predictions of the theoretical study, and to analyze the influence of crystallization and solidification kinetics on the microstructural features of this amorphous alloys. For this purpose, first, glass forming ability of Fe &
#65533
(Mo, B, Cr, Nb, C) &
#65533
X ( X = various alloying elements, selected from the periodic table) ternary alloy systems were simulated for twenty different alloy compositions by using the electronic theory of alloys in pseudopotential approximation and regular solution theory. Then, by using the results of the theoretical study, systematic casting experiments were performed by using centrifugal casting method. The alloying elements were melted with induction under argon atmosphere in alumina crucibles and casted into copper molds of different shapes. Characterization of the cast specimens were performed by using DSC, XRD, SEM, and optical microscopy. Comparison of equilibrium and nonequilibrium solidification structures of cast specimens were also performed so as to verify the existence of the amorphous phase. Good agreement of the results of experimental work, with the predictions of the theoretical study, and the related literature was obtained.
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Arslan, Hulya. "Synthesis And Characterization Of Nickel Based Bulk Amorphous Alloys." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/3/12605099/index.pdf.
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The aim of this study is to synthesize and characterize new bulk amorphous alloys in the Ni- based systems. Theoretical studies on the basis of semi-empirical rules and the electronic theory of alloys in pseudopotential approximation has been provided in order to predict the impurity elements that will lead to an increase in the glass forming ability of Ni-based alloy systems. Glass forming ability of ten different compositions of alloys of Ni-Nb, Ni-Fe, Ni-B, Ni-Hf and Ni-Cr was simulated by using FORTRAN programs based on pseudopotential theory. In addition to the binary alloys, ternary alloys, which were formed by addition of 1 at% of third element to these systems, were also simulated. Since ordering energy is an indicator of glass forming ability, theoretical studies allowed to predict the effect of various third elements on the formation of amorphous phase. Furthermore, ordering energies were also used to calculate other parameters important for glass forming ability. In the second part of the study, on the basis of theoretical results, a series of casting experiments were done. Different compositions of Ni-Nb, Ni-Nb-Sn and Ni-Nb-Al alloys were cast in the centrifugal casting machine. Alloys were melted in alumina crucibles and cast into the copper moulds. Characterizations of cast alloys were done by the use of Metallography, SEM, XRD and DSC. Fully amorphous Ni52Nb41Al7 alloy was synthesized in bulk form with 0.8 mm thickness.
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Plundrák, David. "Analýza příčin vzniku trhlin v ráfcích kol." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230459.
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This thesis looks for the causes of cracks in bicycle rims in the most stressed areas (in places holes for wires). For this reason, in this work is the stress and strain analysis of a simple model of the rim to the working load is given and further the complete production process of the rim is described. As an experimental material were used rims from different producers of aluminum alloy EN AW 6061 and EN AW 6082 T6 temper, in which a crack started to spread. For assessment of rims materials the methods of optical spectroscopy, optical microscopy, scanning electron microscopy, Vickers hardness test were used and for finding another crack penetration test was performed. Based on the performed experiments bad design solution of rivets was found in the rim 1. Broken rivets initiated fatigue cracks. Material of rim 1 was alright. The other two rims were deficiencies in materials. For the rim 2 was a problem with coarse-grained recrystallized structure. The insufficiently rapid cooling for the rim 3 caused exclusion hardening phase (particularly copper phase) at grain boundaries. Moreover, the rim 3 is not cured to the required parameters. Aluminium alloys are an ideal material for bicycle rims. However, they require reliable design solutions and meeting the physical metallurgy, which lies in the knowledge and use of influences of chemical composition, forming and heat treatment on mechanical, chemical, physical and technological properties.
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Nytra, Michal. "Simulace zápustkového kování pomocí metody konečných prvků." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400519.
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Tato diplomová práce se zabývá výpočtovým modelováním zápustkového kování, které patří do metod objemového tváření zatepla. Cílem je změnit běžnou praxi tvorby výpočtových modelů ve specializovaných softwarech na bázi metody konečných prvků (MKP) a sestavit výpočtový model v MKP softwaru Abaqus. Pro výpočet jsou zde použity deformační varianta MKP a explicitní algoritmus. Řešenou součástí je ozubené kolo automobilové převodovky. V rámci práce je vytvořena rešerše z oblasti objemového tváření včetně specializovaných programů pro simulace procesů tváření. Dále jsou v práci uvedeny všechny konstitutivní vztahy pro popis elasto-plastického modelu materiálu s tvárným porušením. Následuje teorie přenosu tepla, jsou popsány všechny způsoby jeho realizace s jejich matematickými formulacemi včetně metod řešení. Klíčovou je kapitola popisující postup tvorby výpočtového modelu v softwaru Abaqus od tvorby geometrie až po okrajové podmínky. Následuje analýza dosažených výsledků a práce je zakončena výhledem na možné pokračování v tomto tématu.
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Ntsendwana, Bulelwa. "Advanced low temperature metal hydride materials for low temperature proton exchange membrane fuel cell application." Thesis, University of the Western Cape, 2010. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8494_1307431585.
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Energy is one of the basic needs of human beings and is extremely crucial for continued development of human life. Our work, leisure and our economic, social and physical welfare all depend on the sufficient, uninterrupted supply of energy. Therefore, it is essential to provide adequate and affordable energy for improving human welfare and raising living standards. Global concern over environmental climate change linked to fossil fuel consumption has increased pressure to generate power from renewable sources [1]. Although substantial advances in renewable energy technologies have been made, significant challenges remain in developing integrated renewable energy systems due primarily to mismatch between load demand and source capabilities [2]. The output from renewable energy sources such as photo-voltaic, wind, tidal, and micro-hydro fluctuate on an hourly, daily, and seasonal basis. As a result, these devices are not well suited for directly powering loads that require a uniform and uninterrupted supply of input energy.
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Allo, Justine. "Mécanismes fondamentaux et cinétiques d'oxydation d'alliages réfractaires de nouvelle génération pour la prétrochimie." Thesis, Normandie, 2021. http://www.theses.fr/2021NORMR005.
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Tomeček, Vojtěch. "Využití metody konečných prvků pro modelování šíření hlasu vokálním traktem a okolo hlavy člověka." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230941.
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This diploma thesis deals with creating of finite element model for the analysis of acustic waves radiation through human vocal tract and through the head surrounding space. The thesis contains a short overview of the anatomy of relevant parts and a short overview of formerly published models relevant to the topic. Then the process of creating the 3D model of human head, including the vocal tract, based on CT scans, and the mesh itself follows. This is succeeded by the computational solution taking in the acount the acoustic absorption of the vocal tract walls and radiation into the open space. The results gained are compared to relevant literature on this topic. The changes in frequency spectra in specific nodes of the mesh are reviewed and compared to relevant literature on the topic. The results could be used as basis of eventual frequention corrections of microphones used for voice diagnosis or registration in general, eg of speach or singing.
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De, Gaetano Giovanni. "A regularized arithmetic Riemann-Roch theorem via metric degeneration." Doctoral thesis, Humboldt-Universität zu Berlin, 2018. http://dx.doi.org/10.18452/19227.
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Das Hauptresultat dieser Arbeit ist ein regularisierter arithmetischer Satz von Riemann-Roch für ein hermitesches Geradenbündel, die isometrisch zum Geradenbündel den Spitzenformen vom geraden Gewicht ist, auf eine arithmetische Fläche, deren komplexe Faser isometrisch zu einer hyperbolischen Riemannschen Fläche ohne elliptische Punkte ist.
Der Beweis des Resultats erfolgt durch metrische Degeneration: Wir regularisieren die betreffenden Metriken in einer Umgebung der Singularitäten, wenden dann den arithmetischen Riemann-Roch-Satz von Gillet und Soulé an und lassen schließlich den Parameter gegen Null gehen. Durch die metrische Degeneration entsteht auf beiden Seiten der Formel ein divergenter Term. Die asymptotische Entwicklung der Divergenz berechnet sich auf der einen Seite direkt aus der Definition der glatten arithmetischen Selbstschnittzahlen.
Der divergente Term auf der anderen Seite ist die zeta-regularisierte Determinante des zu den regularisierten Metriken assoziierten Laplace-Operators, der auf den 1-Formen mit Werten in dem betrachteten hermitischen Geradenbündel operiert. Wir definieren und berechnen zuerst eine Regularisiereung des entsprechenden zu den singulären Metriken assoziierten Laplace-Operators; diese wird später im regularisierten Riemann-Roch-Satz auftauchen. Zu diesem Zweck passen wir Ideen von Jorgenson-Lundelius, D'Hoker-Phong und Sarnak auf die vorliegende Situation an und verallgemeinern diese.
Schließlich beweisen wir eine Formel für den zum betrachteten hermitischen Geradenbündel assoziierten Wärmeleitungskern auf der Diagonalen bei einer Modellspitze. Diese Darstellung steht im Zusammenhang mit einer Entwicklung nach zur Whittaker-Gleichung assoziierten Eigenfunktionen, die im Anhang bewiesen wird. Weitere Abschätzungen des zum betrachteten hermitischen Geradenbündel gehörigen Wärmeleitungskern auf der komplexe Faser der arithmetischen Fläche schließen den Beweis des Hauptresultats ab.The main result of the dissertation is an arithmetic Riemann-Roch theorem for the hermitian line bundle of cusp form of given even integer weights on an arithmetic surface whose complex fiber is isometric to an hyperbolic Riemann surface without elliptic points. The proof proceeds by metric degeneration: We regularize the metric under consideration in a neighborhood of the singularities, then we apply the arithmetic Riemann-Roch theorem of Gillet and Soulé, and finally we let the parameter go to zero. Both sides of the formula blow up through metric degeneration. On one side the exact asymptotic expansion is computed from the definition of the smooth arithmetic intersection numbers. The divergent term on the other side is the zeta-regularized determinant of the Laplacian acting on 1-forms with values in the chosen hermitian line bundle associated to the regularized metrics. We first define and compute a regularization of the determinant of the corresponding Laplacian associated to the singular metrics, which will later occur int he regularized arithmetic Riemann-Roch theorem. To do so we adapt and generalize ideas od Jorgenson-Lundelius, D'Hoker-Phong, and Sarnak. Then, we prove a formula for the on-diagonal heat kernel associated to the chosen hermitian line bundle on a model cusp, from which its behavior close to a cusp is transparent. This expression is related to an expansion in terms of eigenfunctions associated to the Whittaker equation, which we prove in an appendix. Further estimates on the heat kernel associated to the chosen hermitian line bundle on the complex fiber of the arithmetic surface prove the main theorem.
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HSU, JU-FENG, and 徐如鋒. "The Forming Analysis of Phillips Drive Countersunk Head Screws." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/19180462467741560021.
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碩士高苑科技大學
機械與自動化工程研究所
104
This study is aimed at AISI 1022 low carbon steel billets to investigate experimentally the forming characteristics and stress responses of horn head and dual-horn head Phillips drive countersunk head screws. The forming experiments are conducted on tensile-compression test machine by simulating the forming model of one die-two blow heading machine. It is revealed experimentally that, to form a Phillips drive countersunk head screws, firstly to form a horn head and punching a small square hole for the first blow, secondly to punch the countersunk for the second blow. For the second blow, the four corners of the punch have to align with the four corner of square hole on the head of the billet to form a symmetric circular head. For horn head and dual-horn head, since the second cone is forming a little as forming the horn head for the first blow, the forming forces are not distinct obviously. While, as punching the countersunk with a Phillips punch for the second blow, the forming forces are increased rapidly due to the strain hardening effect, especially for dual-horn head, which forming force is much larger than that for horn head.
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Chan, Chih-Chiuan, and 陳志權. "Improvement of Forming for a T-Head Bolt by Taguchi Method." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/36579677440020227481.
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碩士國立高雄應用科技大學
模具工程系碩士班
101
The forming of head on T-Head bolt is produced by three-stage cold forming processes. Because the height of compression rate of head is high as 85.5% during forging process, this situation is easy to occur surface crack and that will have great influence on the product quality after forming. In this study, try to find out optimal forming parameters to reduce the surface crack on the bolt in the forming process. Pro / Engineer is used to construct geometry of billet, bolt and die. DEFORM-3D is adopted to simulate the three-stage cold forging processes and to analyze die stress to find out effetive parameters of each-stage forging process. Taguchi method L8 (27) orthogonal array is used to integrate all forming parameters to simulate, and find out those high influential factors of forming parameters by analyses of S/N and confidence level. The Taguchi method L9 (34) orthogonal array integrates those high influential factors of forming parameters to analyze again. The combinational parameter of optimization is obtained by analysis of variance (ANOVA) according damage of workpiece and the maximum effective stress of die. Finally, comparing the results of analysis in new design with that in original design, it displays that new forming parameters reduces the forging force about 15%, the value of damage about 24%, and decreases the maximum effective stress of die to improve the service life of die.
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Zhu, Cang Hong, and 朱倉宏. "Analysis of Billet Cutting Surface and Forming for Flanged Socket Head Bolt." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/64eyx7.
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碩士國立高雄應用科技大學
模具工程系
103
Quality of billet cutting surface will affect forming stage on the forming of fastener, including forming load to large, failure and scrap. Therefore, this study focuses on decreasing burrs, deformation and incline of section for billet cutting. This paper uses FMEA to evaluate the billet cutting, the risk priority number (R.P.N) come to the severity of the problem and that any risks may happened and avoid. Drawing the shape of geometry by 3D graphics software and finite element simulation (DEFORM) for verification. Most studies focus on the trimming, it will be a challenge to study the billet cutting. This study in connection with shearing parameters of shear mode to make improvements, such as shears of rate, gap of shear die with eye die and shears of radius, etc. To determine the shearing quality is using cutting load and energy. In this study, the simulation of deformation conditions for billet cutting, and continued the simulation of forming after cutting the billet, it will be find that the forming load increase about 50% in the first stage. Adding the Taguchi method to design the most appropriate condition for shearing. The difference of shearing load reaches as high as 29%.
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Zheng, Yu-Shun, and 鄭宇順. "The Research and Development of Heating Raw Material Within Forming Die for Screw Head." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34k8rz.
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碩士國立虎尾科技大學
機械與電腦輔助工程系碩士班
101
How to develop special alloy fastener products with high price value for better profitability is the top priority that faces Taiwan''s metal forging industry, especially the manufacturers of screws. To face the tougher press forging of special metals, there are the following hot forging press: (1) heating and then forging billets inside the furnace; (2) heating by electromagnetic coil induction, and (3) heating by electric heating rod die. These approaches, however, require forging after heating, and the consequent partial temperature drop can change the material stress. Meanwhile, a direct resistive heating to forge billets inside the mold not only reduces the uneven distribution of material temperature, surface oxidation and surface material coarsening, but also alleviates the stress hike resulted from the material temperature drop during the forging process, thus greatly improves the malleability and mass production capacity of nickel-base superalloy materials. Also, the nickel material is a key factor to the forging process and simulation parameters. In view of this, this research proposes a forging approach that directly heats billets inside a mold. The study comes in four parts: (1) simulation of the bolt head forging process; (2) experiment of the direct resistive heating inside a mold; (3) experiment of the resistive heating inside the mold to forge the bolt head; and (4) experiment of the nickel alloy resistive heating inside the mold to forge the bolt head. The software tools DEFORM-3D and DEFORM-2D are used to simulate the bolt head heating and forging patterns and, based on the simulation results, real molds are built to test the resistive heating inside the molds, followed by tests of resistive heating and forging of bolt heads inside the molds, and finally nickel-based alloy materials are taken for experiment and discussion of the resistive heating and forging of bolt heads. The experiment results show that (1) the direct resistive heating and forging of billets inside the mold is feasible, and using a preload device can correct the poor heating; (2) this research has successfully heated the SCM440 billet, swiftly and directly, up to 1100℃ for the bolt head forging process, thus proposed a gradual heating pattern to improve the filling of the bolt head forging; (3) when this approach is applied to 718 and C276 nickel alloys, the heating pattern is different from that with SCM440, causing the overall temperature of the billet unable to reach the forging temperature or causing the billet''s partial temperature over the melting point, resulting in failed forging.
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Chang, Yi-Hung, and 簡亦鴻. "Improvements of Forming and Die for High Strength Flanged Socket Head Bolt by Taguchi Method." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/ffde2a.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系碩士班
102
Increase the added value of products is focused on the transformation of Taiwan's fastener industry, the production of high strength fasteners will help to enhance the added value of products, in order to develop products with high strength fasteners, the production design is appropriately shaped necessary. This study assessed based on high strength hex flange bolts FMEA forming problems , the risk priority number (RPN) came to the severity of the problem, and then using commercial graphics software Pro / Engineer parametric way to construct billet die etc. geometry, import finite element analysis software DEFORM 3D to analyze forming and die stress, and establish a high strength flanged socket head bolt forming limit and mold design standards. In this study, forming and die for high strength flanged socket head bolt designed to make improvements , for example , to determine the quality of the head forging billet diameter ratio of the volume of billet、forging flow line installation stress ring, etc. In order to provide subsequent developers do use and reference.In this paper, the Taguchi method to reduce the third pass, the goal of forging force.The optimal combination of parameters is obtained by S/N analysis and the analysis of variance , the study of flanged socket head bolt forming the design is complete , and effectively reduce the strength of forging the third 29%.
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LI, PEI CONG, and 李沛璁. "Design and Analysis of Forming and Die for the High-strength Hexagon Socket Head Bolt." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/63258099400980391560.
Full textAbstract:
碩士國立高雄應用科技大學
模具工程系碩士班
102
Hexagon socket head bolt are the most common high-strength fasteners in the market. With the increasing requirement of the strength of fasteners, it has become popular that using Alloy steel as fastener material. In this research, SCM440 is using as material of high-strength hexagon socket head bolt. Commercial graphics software Creo is applying to mold desigh and paremetric modeling . DEFORM 3D is using to analysis the forming and evaluate results by FMEA. Also using risk priority number(RPN) to find out the problem of shaping high-strength hexagon socket head bolt, and so as to improve the research objectives. The first study to avoid the occurrence of buckling secondary molding, and the wire cross-sectional reduction ratio of 50% or less, the outer diameter of 10mm inner hexagon of high strength bolts, wire diameter in the range of its use is recommended to shape 9.5mm ~ 12.7 mm between. Taguchi optimization through the second pass of punch geometry, as well as ahead of the forming head forming amount to 70%, success will be reduced by 10% overall forging energy, and the lack of improvement in the problem of forming filling. And split mold and stress analysis by election to interfere with the proper amount of mold.
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Jiang, Dar-far, and 姜德發. "On the Design of Automatic Film Sealer and Adjustable Bag- Forming Head of an Intelligent Horizontal Form-Fill-Seal Packaging Machine." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/57124109440922276334.
Full textAbstract:
碩士國立成功大學
機械工程研究所
81
An intelligent horizontal form-fill-seal packaging machine is an automatic packaging device equipped with automatic film- sealer and adjustable bag-former. This study presents a syste matic process to design and manufacture such packaging machine with desired performances. Based on the concept of synch-ronous tracking, an automatic film sealer is figured out. Solenoids along with a film fixing and sealing mechanism are used to make the spare film fixed and sealed. Linear bearing and circular guide rail are used for motion guidance. Timing belts and pulleys are employed to transmit power. Electromagnetic clutches together with a gear train are applied to shift the power flow. Servo- motors and a close loop control unit are designed to accomplish the task of tracking and sealing of film sealer. As for the bag-forming device, a four-bar mechanism is synthesized to adjust the blade height of the device. The film- guide-roller position and bag-width adjustment are performed by leader screws. Which are controlled by a step motor and a open- loop control unit. The contribution of the work is beneficial to the systematic design, automation, and improvement of production of packing machine for industry.
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Tsolas, Nicholas. "Thermal Spray Forming of High-efficiency Metal-foam Heat Exchangers." Thesis, 2010. http://hdl.handle.net/1807/25831.
Full textAbstract:
Thermal spray coating processes have been employed in the current study to deposit well-adhered, dense skins onto the surfaces of open-cell metal foams. The result is a channel that consists of a metal foam core and a thermal sprayed skin wall that can be used as a compact heat-exchanger by directing the coolant flow through the foam. To study the feasibility of the metallic foam heat-exchangers, hydraulic and heat-transfer characteristics were investigated experimentally. The local wall and fluid temperature distribution and the pressure drop along the length of the heat exchanger were measured for different coolant flow velocities. The Dupuit-Forchheimer modification is employed with the experimental results to determine flow characteristics. To measure the heat transfer performance, a length average Nusselt number is derived from a volumetric heat transfer coefficient based on the local wall and fluid temperatures. Heat transfer was shown to have increased nearly 7 times compared to that of a channel without a foam core.
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CHAN, CHIA HAO, and 詹家豪. "The Study on In-mold Formingof Flat Head Screws." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/q8663h.
Full textAbstract:
碩士高苑科技大學
機械與自動化工程研究所
106
In this study, by simulating three-stage forming machine, the forming force and formability of flat head screws are investigated experimentally and numerically. The numerical simulation of three-stage forming is studied by using FE code of DEFORM-3D. To forming a larger head of screw, a billet with larger diameter is used. The first stage is to extrude a billet into smaller diameter rod. The second stage is pre-forming of head. The third stage is in-mold forming of flat head. It is revealed experimentally and numerically that, for stage 1, the extrusion forming is not affected by the length of billet; for stage 2, the billet is freely bulged in the cylindrical cave of punch, and forming force is similar to stage 1. When the billet is not completely bulged, it is likely to cause a significant crease on the head in stage 3 of in-mold forming of flat head. Therefore, in order to upset a complete circular flat head in stage 3, the billet should be bulged completely in stage 2 of head pre-forming. The more is the pre-forming billet, the larger flat head is formed. The stage 3 is to in-mold upset the billet into a complete cylindrical head. The stroke is shortest, but the forming force is largest. Particularly, when the billet is compressed to reach the inner wall of the die, the forming force varies dramatically. The larger outer diameter is the head, the greater forming force is required. The forming force of stage 3 is much larger than stage 1 and 2, and the of punch and die for stage 3 is thus less, and leads to the loss of related parts of operating forming machine. Keywords: Three-stage forming machine, flat head screw, in-mold forming, forming force.
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Shen, Chih-Hung, and 沈志宏. "Study on the influence of forming process to heat pipe’s performance." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/r2mxqz.
Full textAbstract:
碩士大同大學
機械工程學系(所)
95
ABSTRACT Heat pipe use of liquid and vapor. Two phase flow heat transfer, has been exercised in electronic cooling since 90’s. The mean study of thesis is to find out the performance curve after heat pipe forming process. Tracking the decayed range of heat pipe by a series of the related experiments. Build up the experimental trend as an engineering reference for designing thermal module of electronic components. The research is to focus on the effect of heat pipe forming process including flatting, bending and both . The influence of deform about different wick structure (mesh, groove and powder ) of heat pipe , and different diameter (Ф4, Ф5 and Ф6 ) heat pipe’s forming limits of performance are also analyzed. In this study, three parameter of heat transfer is detected. They are ΔT (2 points temperature difference), Qmax (Maximum Heat Transfer) and Q” max (Maximum Heat Flux). Comparison of each result is carried to get the deformation effects on heat pipe before and after. The result of experiment shows that the mesh structure will support better flatting limits, eachψ4, ψ5 andψ6 mesh pipe can press to 2.0 mm thickness, but groove and powder type just support 2.5 mm deformation. About the bending , the groove and powder type will tolerate the smaller bending radius (Rc) in each different heat pipe diameter on the contrary. When both two processes are applied on the performance will be decreased for bending angle (θ) less than 90 degree.
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Liu, Jiying. "Friction and heat transfer models for finite element simulation of metal forming." 2004. http://etd.nd.edu.lib-proxy.nd.edu/ETD-db/theses/available/etd-07162004-094550/.
Full textAbstract:
Thesis (Ph. D.)--University of Notre Dame, 2004.Thesis directed by Steven R. Schmid for the Department of Aerospace and Mechanical Engineering. "July 2004." Includes bibliographical references (leaves 117-120).
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Wu, Li-Jen, and 吳立仁. "Study on Simulation and Analysis of Heat Bending for Forming Steel Plates." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/00193984187996184492.
Full textAbstract:
博士國立成功大學
造船及船舶機械工程學系
90
The heat bending process has long been used for plate forming in the metal forming and shipbuilding industries, and has always depended on skilled workers. Since metal forming and shipbuilding companies need a reduction in production costs and in the number of workers they employ, an increased use of automation is desirable. This study discusses a laser source and an oxyacetylene torch source. The heat input intensity, Q, the speed of the servomotor, V, the constraint conditions, the heating paths, the heat affected zone, the temperature field, the cooling rate, , and the dynamic displacement of the plate during heat bending etc. are all discussed. Thermoplastic theories, three-bar analysis, and two dimensional temperature fields are used to study control methods and to simulate the heat bending processes. This paper considers the advantages of applying Grey and Fuzzy theories to the analysis and simulation of the heat bending process for steel plates by using a Grey predictor and an on-line Fuzzy controller. A Grey predictor is applied to assist in the prediction of the temperature within the steel plate, and in the analysis of its thermoplastic characteristics. The temperature of the steel plate at the next measuring data point is predicted, and this information can then be used as feedback within the controller. The Grey method uses four types of modeling algorithm with G(1,1) methods. These algorithms are constructed, discussed, and compared using different temperature dimensions, M, where M lies between 4 and 100. The four kinds of Grey G(1,1) modeling methods are the New-Dimension G(1,1) Grey Method (NDGM), the New-Dimension-Zero-First-Term G(1,1) Grey Method (NDZFTGM), the Same-Dimension G(1,1) Grey Method (SDGM), and the Same-Dimension-Zero-First-Term G(1,1) Method (SDZFTGM). The best prediction method of the boundary temperature is proven to be the SDZFTGM, and the optimal dimensions, M, of the temperature series are found to be 4 and 5. Under these conditions the error is under 2%, which is lower than the error given by the three other kinds of Grey methods. The fuzzy controller was developed based upon the simulation of the temperature field and the physical behaviors manifested in experimentation. The fuzzy controller fine-tunes the torch speed, V, by applying a set of rules and a set of membership functions. The results of the experiment verified the use of a fuzzy controller in heat bending experiments. The conditions of heat bending using 12 heating lines, and the values of during the heat bending experiments. The experimental results discussed in this paper use the conditions with fuzzy control to bend a plate into the required shape and to prove the performance of the heat bending fuzzy controller. During the heat bending process the average displacement along 10 measuring lines was compared with the displacement of the required shape. It was found that there was an 8% error in displacement. It was found that a fuzzy controller is effective in governing the speed of the servomotor driving the heat source.
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Lin, Ming-Wen, and 林明文. "Study on the Control System of the Heat-forming for the Ship Plate." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/22474537127668687212.
Full textAbstract:
碩士國立成功大學
造船及船舶機械工程學系
87
Skillfull techniques of Shipbuilding is not easy to pass on, but automation is needed in the heat-forming process. The main affected factors are needed to study for heat-bending in working process. According to studies, the main deformation factors of heat-bending depends on the intensity of source, various temperature and moment speeds. The parameters aren’t adjusted in conventional heat-forming system. Because of the reason, we study the fuzzy system to strengthen digial and numerical control system. The result of the simulations and measured information of sensors are obtained in order to calculate the intensity of source and moment speeds for adjusting freeback data and monitoring deformation in the system. PID and controller are very well in the conventional control methods but they need a good mathematics model to prove the effect. The truthful System State can not be understood in general physical system. Heat-bending forming process is a complex environment and is very difficult to control. It is more difficult to show the model from complete mathematical methods and to calculate different heat-bending process. Therefore, the paper has solved the control system of the heat forming for ship plates by experiments and simulations.
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YEN-CHIN, FENG, and 馮彥琴. "Studies on heat gel-forming ability during process of muscle protein from squid." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/05347542686184667878.
Full textAbstract:
碩士國立屏東科技大學
食品科學系
92
Golden fish roe, fish balls and other surimi products are mainly made of fishes in Taiwan distribution channel. Only few products are made of squids or other invertebrates. One of the reasons is that fishes have better forming ability than squids for making surimi. Therefore, the topic was chosen study on improving squid gel-forming ability. The first step was to investigate neritic squid meat paste gel-forming ability and appliance and used two-step heating to improve gel-forming quality. Then, it was studied that what facts protein hydrolysis enzyme effected heat gel-form in squid meat paste in this research. Also, it was studied that how to improve heat gel-forming ability by adding protease inhibitor and characteristics of protein hydrolysis enzyme. By using fresh neritic squid as a raw material, the first step was to take off skin and made muscles to meat paste and added some protease inhibitors. Then, the sample were heated under the different conditions (one-step heating：70 degree for 20 minutes；two-step heating：24-25 degree for 30 minutes and 70 degree for 30 minutes) until it became gel-form. After that, the strength of gel-form was examined by texture analyser. Then it melted gel-form and surimi by using SDS-PAGE to study protein components. Additionally, in order to understand characteristics of protein hydrolysis enzymes, by using 20mM Tris-HCl to take out muscles surimi to analyze the crude enzyme drops. In this research, it was studied that reaction temperature of crude enzyme drops, pH, salt consistency and added marlin protein liquors to check how they decomposed. Neritic squid meat paste had the highest strength at 70 degree and to increase temperature was not effective to gel-form too much and heating time had limited effects. It was also found that two-step heating caused gel-form’s strength badly, but if it added Soya trypsin inhibitor, EDTA, PMSF to two-step heating, the results showed that gel-form had better strength. Then, it was also found that the crude enzymes activity was the most active around pH neutral. The best temperature for cow’s serum protein was at 40 and 70 degree and for casein was at 35 and 70 degree. Both of them were the most active in salt consistency 0.11M. Therefore, neritic squid’s gel-forming ability was related to metal protein hydrolysis enzyme due to the previous researches. In this experiment obviously indicated that protein of pancreatin was higher related to protein hydrolysis enzyme.
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LI, Wen-Yao, and 李文堯. "Study on Hot Extrusion Forming and Thermal Resistance of Magnesium Alloy Heat Sinks." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/17917925998258317624.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
98
This research mainly focuses on the fabrication of AZ31 and AZ61 heat sinks magnesium alloy parts by hot extrusion. Process parameters considered in this study are heating temperature of billet and extrusion speed. The influence of process parameters on extrusion load is discussed. Meanwhile, extrusion experiments under different process parameters are carried out, the effects of process parameters on mechanical properties of the products are analyzed. The mechanical properties discussed in this study are thermal resistance and bending curvature of magnesium alloy heat sinks. The comparion of thermal resistance of AZ31 and AZ61 magnesium alloys and that of A-6061 aluminum alloys are carried out. Material flow pattern of the billet inside the die cavity is analyzed by using a commercial finite element package“DEFORM 3D”. Stress and strain distribution of material in the die cavity, bending curvature of the products after extrusion are investigated. The experimental results are compared with the analytical values to verify the validity of the proposed analytical models.
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chen, cheanjung, and 陳俊榮. "Inverse Heat Transfer Analysis and Grey Temperature Forcasting in Thermal Mechanical Forming of Plates." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/04718654259731408918.
Full textAbstract:
碩士國立成功大學
造船工程學系
86
Industrial applications of metal plate forming processes are numerous.Thermo-mechanical methods,primarily of line heating, have been used extensivelyfor shipbuilding application for many years. However,the decreasing number of such highly skilled craftsmen, who have developed the art of determining how and where to apply the heat to produce desired shapes in a plate, coupled with the continuing reequirements of the shipbuilding industry, has emphasized a need for the developement of new thermo-mechanical forming techniques. The parameter values defining the distortion and temperature are related to process variables : the thermal power and speed of travel of the heat source.This paper presents a numerical method that analyzes direct and inverse heat problems to solve the distribution of temperatures and heat source when the boundary of work piece is moving source. In addition, applying Grey System Theory to predictthe trend of data of experimental temperature. After getting the relationship among thermal power, speed and temperature, the database can be built. The result shows that the objective is expected.
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Novita, Felicia Januarlia, and 沈惠麗. "Heat-Integrated Design of Formic Acid Production via Reactive Distillation Configuration." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/10751875082120469527.
Full textAbstract:
碩士國立臺灣科技大學
化學工程系
101
The heat-integrated design of formic acid production via reactive distillation (RD) configuration will be investigated in this thesis. The design for this process refers to Huang’s process and it is optimized to obtain a better process design that has the minimum total energy. Later on, design which is optimized will be used as reference by the other configuration to reduce the “remixing effects” phenomena which may occur. The first approach is the thermally coupled configuration. As the results, the “remixing effects” can be reduced and minimum total energy less than the base case and optimization design can also be achieved. This research also investigates another heat-integrated method. It is external heat integration which uses the heat of top distillate vapor in one column to transfer the heat to side heater and/or to the reboiler of another column. The results for this method are better than the thermally coupled one because the total energy can be further reduced compared to thermally coupled design.
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Li, Chia-Chun, and 李佳純. "Application of high-resolution melting-based DNA marker analysis in rapid detection of heat-tolerant curd-forming broccoli genotypes." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/72928399681296635553.
Full textAbstract:
碩士國立彰化師範大學
生物技術研究所
104
In agricultural seedling industry, the link of genetic molecular markers to special characteristics can help crop development and increase its competitiveness in the international market. However, there are two bottlenecks needed to be overcome. First, the development of molecular markers often uses non-specific random primers which may produce less reproductive result. Second, to conduct these analyses may require a lot of time and manpower. Broccoli ( Brassica oleracea var. italica ) is an edible green plant in the Brassicaceae family. The optimal growth temperature is 22 ℃ while curd formation occurs below 18 ℃. Based on the days needed for curd formation, cultivars are classified into ''early '', ''middle'', and ''late'' groups. There are some cultivars belong to early group that were heat tolerant and can have curd formation at the temperature of 25 ℃ and above. Many molecular markers like RAPD, SSR markers have been already used to idenfy these heat tolerant groups. In this study, High Resolution Melting Curve ( HRM ) in real - time PCR was used to distinguish heat - resistant early - sprouting groups from other groups using specific primer pairs in a very short time period. In this study, two markers derived from Cox19 - like CHCH family and Flowering locus C promoter were used for analyses using HRM. Based on the spectrum difference between early - sprouting cultivar and late - sprouting cultivar in the HRM analysis, we can apply this method to screen heat - resistant cultivars as well as to test the purity of hybrid seed generated from different parental groups in a short time perid.
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Wu, Shyh-Chi, and 吳世基. "The effects of the flow forming and heat treatment on the mechanical properties of D6AC steel electron beam weldments." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/01318642157968598700.
Full textAbstract:
博士國立交通大學
機械工程學系
100
The objective of this research is to investigate the effect of flow-forming process, heat treatment, and EB welding on the mechanical properties and microstructure of D6AC ultrahigh-strength steels. Therefore, a group of optimum manufacturing parameters can be determined and will be applied to the development of aerospace and defense industries. In the present study, the cold forward flow forming technique and EBW process were employed to fabricate the tube and to join the tubing pieces, respectively. Various process parameters were incorporated to combat the problem of inadequate ductility associated with the weldment fabricated from the D6AC steel. These included varying the input amount of cold forming, EBW and trying different post-weld heat treatments. The present study showed that the D6AC steel tube produced by the forward flow forming technique had an increased mechanical strength but a decreased ductility, as the amount of flow forming was increased. In the case of 78% flow forming input, the mechanical strength of the steel was elevated by 0.4% but the percentage elongation markedly deteriorated by 8.1% after the steel was post-weld heat treatment at the temperature of 350℃. Subsequent to EB welding, likewise the D6AC steel showed an enhanced mechanical strength but a deteriorated ductility. This suggested that the heavily flow formed D6AC steel can not be used for a direct EB welding. For the D6AC steel that had received the flow forming amount of 78%, the steel for the temperature range of after 250℃～650℃ post-weld heat treatments. Among these, the 350℃post-weld heat treatment temperature had a great mechanical properties. However, the percentage elongation decreased to start with and then increased as the temperature was increased. The highest percentage elongation 13.2% occurred at testing temperature of 650℃. The study has demonstrated that D6AC steel is a suitable material for manufacturing seamless thin-wall tubing through the cold forward flow forming technique. After a 350℃ post-welding heating, the steel can deliver superior mechanical properties. However, the D6AC steel has been found not suitable for EB welding directly after cold flow forming, because the weldment of the cold formed steel may suffer a serious inadequacy of percentage elongation. As a result of the present research, the sticky problem associated with lack of ductility of the D6AC steel that used to trouble the aerospace and defense industries has been solved. Post-weld heat treatment is necessary to reduce the residual stress and improve the mechanical properties of the EB weldment.
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Jílková, Veronika. "Lesní mravenci rodu Formica jako významní ekosystémoví inženýři." Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-352953.
Full textAbstract:
This thesis consists of one chapter accepted for publication in a book and four papers published in international journals with impact factors. All of the contributions deal with the role of wood ants in energy and nutrient fluxes in forest ecosystems. Wood ant nests are known as hot spots of carbon dioxide (CO2) production and are also thought to affect methane (CH4) flux. Stable high temperatures are maintained in ant nests even in cold environments. This study is focused on quantification of CO2 and CH4 flux in wood ant nests, contribution of ants and microbes to CO2 production, properties of nest material that affect CO2 production and the role of ants and microbes in the maintenance of nest temperature. The research was conducted in temperate and boreal forests inhabited by wood ants (Formica s. str.). Gas fluxes were measured either by an infrared gas analyser or a static chamber technique. Ants and nest materials were also incubated in a laboratory. Material properties potentially influencing CO2 flux, such as moisture, nutrient content or temperature were determined. According to the results, CH4 oxidation was lower in wood ant nests than in the surrounding forest soil suggesting that some characteristics of ant nests hinder CH4 oxidation or promote CH4 production. Wood ant nests clearly are hot...
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Kadochová, Štěpánka. "Termoregulace mravenců rodu Formica, konflikt jedince versus kolonie." Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-370961.
Full textAbstract:
This thesis deals with thermoregulation in red wood ants, in Formica rufa group. Our aim was to better understand the mechanisms by which red wood ants maintain thermal homeostasis in their nests. Red wood ants are known to keep high and stable temperatures in their nests from spring to autumn. Most emphasis is placed on the role of the nest mound as a solar collector or on a heat production by microbial community present in the nest material. However, some researchers believe that wood ants are able of active nest thermoregulation in which they can affect the nest temperature by behavioural reactions, mainly by sun basking, increased metabolic heat production or heat transport. The thesis consists of three research articles. The first one is focused on the timing of thermoregulation in red wood ants, the second one investigates in more detail one specific aspect of red wood ant thermoregulation - a sun basking behaviour. These two papers provide data from long-term field observations and experiments. The last paper is based on laboratory experiments where we tested a hypothesis resulting from field observations. Thanks to the field research we found out that ant activity (traffic on ant trails) significantly correlates with nest temperature; once the activity decreased the thermal homeostasis...
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Chou, Pai-Hung, and 周百鴻. "Promotion of Formic Acid Oxidation Performance of Carbon-Supported Pd and Pd-based Nanoparticles by Heat Treatment." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/85716957624668441252.
Full textAbstract:
碩士國立中央大學
材料科學與工程研究所
105
In order to promote energy density and overcome the fuel crossover on the membrane, formic acid is considered to be an attractive fuel at the anode of polymer electrolyte membrane fuel cells (PEMFCs). Besides, the low Pt content PtPd bimetallic catalysts have been investigated due to their high catalytic activity of formic acid oxidation reaction (FAO). In this study, the carbon-supported Pd, PdPt and PdRuPt have been prepared and PdPt, PdRuPt have been heat-treated. The relationship between their surface compositions and electrochemical properties is elucidated. The lattice structures, surface compositions, chemical compositions, morphologies and electrochemical properties of prepared catalysts are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma-optical emission spectrometer (ICP-OES), high resolution transmission electron microscopy (HRTEM), and rotating disc electrode (RDE), respectively. This study is divided into two parts. In the first part, carbon-supported Pd, PdPt and PdRuPt nanoparticles have been prepared at the same reduction condition. The XPS and CO stripping results reveal the small amount of Pt coverage on the surface of PdPt and PdRuPt. The addition of Pt into Pd catalysts have demonstrated great promotion of FAO performance compared to Pd/C, and Ru addition further enhances the CO tolerance of catalysts. Besides, the ratio between forward and backward peak current (If/Ib) of Pd is much higher than those of PdPt and PdRuPt, due to CO poisoning at low potential during forward scan of surface Pt. In the second part, carbon-supported PdPt and PdRuPt catalysts have been heat-treated under CO and O2 atmosphere. Based on the analysis of the XRD, XPS and electrochemical measurement, the change of surface composition during heat treatment, and the correlation between surface composition and catalytic properties of PdPt and PdRuPt catalysts is methodically elucidated. The amounts of surface Pt is related to FAO performance. O2 heat treatment can promote the FAO performance but does not have positive effect on their stability based on the chronoamperometric (CA) results. On the other side, owing to the Pt surface segregation and reduction by CO heat treatment, the mass activity (MA) after CA tests is enhanced, especially for the ternary one.