Dissertations / Theses on the topic 'Weak force'
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Colleoni, Marta. "Gravitational self-force and the weak cosmic censorship." Thesis, University of Southampton, 2016. https://eprints.soton.ac.uk/401825/.
Full textHyde, G. "Ab initio studies of weak force mediated molecular enantioselectivity." Thesis, University of Cambridge, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.604912.
Full textHammond, Giles Dominic. "Development of a spherical superconducting torsion balance for weak force physics." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393048.
Full textCerniway, Matthew Allen. "Elliptical Diamond Milling: Kinematics, Force and Tool Wear." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-20020104-082326.
Full textMachining with diamond tools, whether turning or milling has proven itself as themanufacturing process that produces the highest quality surface finish, with the leastamount of form error in the minimum amount of time. However, due to tool wear and theamount of force generated during conventional machining, diamond tools cannot be usedon carbon containing materials such as steel and brittle materials such as silicates. In anattempt to by-pass the material limitations of diamond machining, a new machiningprocess called vibration assisted machining (VAM) has been developed. VAM involvesoscillating the diamond tool, bringing it into and out of contact with the material in rapidsuccession. VAM can either be 1-dimentional (1D), oscillation in a single direction, or 2-dimensional (2D), a summation of two independent tools motions. Currently, researchefforts are focused on 2D vibration machining, 2D tool motion haven been shown to besuperior to 1D tool motion. Over the past 10 years, 2D VAM with diamond tools hasbeen demonstrated to reduce the amount of machining force and increase tool life whenmachining carbon-containing materials over that of conventional machining processes.However the mechanisms of this improvement have yet to be discovered. This researcheffort is focus on: 1) discovering the fundamental mechanical principals behind theimprovement, force reduction and tool wear, 2) developing a model that predicts thecutting forces and tool contact times, 3) establishes guidelines for the use of vibrationassisted machining and 4) developing an industrial grade 2D VAM servo. The reductionsin tool wear and machining forces are related to the path geometry of the diamond tooland the speed and the depth at which it engages the workpiece. A model has beendeveloped and experimentally verified for 2D VAM which predicts the machining forcesand workpiece / tool contact time if the material properties are known. Along with themodel, a set of charts has been developed for both 1D and 2D VAM that relate the keymachining variables to one another. Lastly, a robust 2D VAM diamond tool servo hasbeen designed.
Samad-Suhaeb, Mujahid. "Aerodynamics of battle damaged finite aspect ratio wings." Thesis, Loughborough University, 2005. https://dspace.lboro.ac.uk/2134/10736.
Full textKnünz, Sebastian. "A trapped-ion phonon laser and the detection of ultra-weak forces." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-127157.
Full textCollop, Andrew Charles. "Effects of traffic and temperature on flexible pavement wear." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336400.
Full textLatifzada, Mushtaq Ahmad. "Estimation of flank wear growth on coated inserts." Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-210994.
Full textBao, Wei-yu. "Tool cutting force modeling and wear estimation of micro-end-milling operations." FIU Digital Commons, 1999. http://digitalcommons.fiu.edu/etd/1386.
Full textWaldura, Markus. "Monomotivik, Sequenz und Sonatenform im Werk Robert Schumanns /." Saarbrücken : Saarbrücker Druckerei und Verlag, 1990. http://catalogue.bnf.fr/ark:/12148/cb35419828q.
Full textVyas, Mukesh Kumar. "Nanoscale Investigation of Adhesion, Friction, and Wear in Chemically Heterogeneous Responsive Polymer Brushes." Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1226414812035-21826.
Full textHaff, G. Gregory, Janna R. Jackson, Naoki Kawamori, Jon M. Carlock, Michael J. Hartman, J. Lon Kilgore, Robert T. Morris, Michael W. Ramsey, William A. Sands, and Michael H. Stone. "Force-Time Curve Characteristics and Hormonal Alterations During an Eleven-Week Training Period in Elite Women Weightlifters." Digital Commons @ East Tennessee State University, 2008. https://dc.etsu.edu/etsu-works/4139.
Full text社本, 英二, Eiji SHAMOTO, 励. 樋野, Rei HINO, 雅之 梅崎, Masayuki UMESAKI, 俊道 森脇, and Toshimichi MORIWAKI. "切削力モデルに基づくエンドミル加工状態の知的認識 (データベースを必要としない手法の開発)." 日本機械学会, 2003. http://hdl.handle.net/2237/9006.
Full textMyint, Tun. "Strength of 'weak' forces in multilayer environmental governance cases from the Mekong and Rhine River basins /." [Bloomington, Ind.] : Indiana University, 2005. http://wwwlib.umi.com/dissertations/fullcit/3167279.
Full textTitle from PDF t.p. (viewed Dec. 3, 2008). Source: Dissertation Abstracts International, Volume: 66-03, Section: A, page: 1153. Co-Chairs: Elinor Ostrom; Patrick O'Meara.
Shatla, Mahmoud Nagui. "Prediction of forces, stressses, temperatures and tool wear in metal cutting." The Ohio State University, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=osu1251224746.
Full textShatla, Mahmoud Nagui. "Prediction of forces, stresses, temperatures and tool wear in metal cutting /." The Ohio State University, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=osu148819211926358.
Full textRizzo, Frank. "Does a Tailored Nine-week Training Intervention Improve Jump Height, Single-leg Stability, and Whole-body Stability Performance in Young Cross-country Skiers?" Thesis, Umeå universitet, Avdelningen för idrottsmedicin, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-181172.
Full textRice, Reginald H. "Atomic force microscopy studies of thermal, mechanical and velocity dependent wear of thin polymer films." Thesis, Kansas State University, 2012. http://hdl.handle.net/2097/14955.
Full textDepartment of Physics
Robert Szoszkiewicz
Nanoscale modifications of polymer surfaces by scratching them with sharp tips with curvature radii of tens of nanometers and at variable temperatures are expected to provide wealth of information characterizing wear response of these polymers. Such studies are important in the light of understanding the nanoscale behavior of matter for future applications in advanced polymer coatings. This thesis describes how Atomic Force Microscopy (AFM) and hot-tip AFM (HT-AFM) methods were used to characterize thermal and mechanical properties of a 30 nm thick film of poly(styrene-block-ethylene oxide), PS-b-PEO, and modify its lamellar surface patterns. Additionally, it is revealed how contact AFM and HT-AFM methods can efficiently characterize the wear response of two popular polymer surfaces, poly(methyl methacrylate), PMMA, and polystyrene, PS. The AFM and HT-AFM studies on PS-b-PEO copolymer were aimed at producing spatial alignment of respective PS and PEO parts. Instead, however, surface ripples were obtained. These measurements are explained using mode I crack propagation model and stick-and-slip behavior of an AFM tip. In addition, HT-AFM studies allowed extraction of several thermo-physical properties of a PS-b-PEO film at local volumes containing about 30 attograms of a polymer. These thermo-physical quantities are: PEO melting enthalpy of, 111 ± 88 J g[superscript]-1, PS-b-PEO local specific heat of 3.6 ± 2.7 J g[superscript]-1K[superscript]-1, and molecular free energy of Helmholtz of 10[superscript]-20 J nm[superscript]-2 for the PEO within PS-b-PEO. Utilizing a spiral scan pattern at constant angular speed and at various temperatures at the AFM tip-polymer interfaces, the wear response of PS and PMMA polymers was characterized. Cross-sections along the obtained spiral wear patterns provided plots of polymer corrugation as a function of scanning speed. From these studies it was found that the corrugation of the modified polymer surface decays exponentially with linear velocity of the scanning tip.
Long, Yu. "Modeling of the effect of tool wear on cutting forces in turning." Connect to this title online, 2008. http://etd.lib.clemson.edu/documents/1211387406/.
Full textSaunders, Nathan William. "Efficacy of a 6-week Neuromuscular Training Program for Improving Postural Control in Figure Skaters." The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1305044478.
Full textSong, Wenge. "Development of predictive force models for classical orthogonal and oblique cutting and turning operations incorporating tool flank wear effects." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16239/1/Wenge_Song_Thesis.pdf.
Full textSong, Wenge. "Development of predictive force models for classical orthogonal and oblique cutting and turning operations incorporating tool flank wear effects." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16239/.
Full textNiu, Zhichao. "Investigation on the multiscale multiphysics based approach to modelling and analysis of precision machining of metal matrix composites (MMCs) and its application perspectives." Thesis, Brunel University, 2018. http://bura.brunel.ac.uk/handle/2438/17549.
Full textCheng, Ming-Yi. "An experimental investigation into tool wear in micro-drilling of aluminium, aluminium/copper metal alloys and carbon fibre reinforced composites." Thesis, Brunel University, 2017. http://bura.brunel.ac.uk/handle/2438/14613.
Full textSamak, Mihir. "Role of Serum Albumin Aggregation in Lubrication and Wear Protection of Shearing Surfaces." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39403.
Full textDoran, Marc C. "Nanoindentation as a Characterization Tool for Wear Resistance in Stainless Steels." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1462807632.
Full textAbsuelo, Ruby. "Employability of Philippine college and university graduates in the United States." Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/868.
Full textBoud, Fathi M. "An investigation of the relationship between temperature, forces and tool wear in turning and drilling." Thesis, Aston University, 1998. http://publications.aston.ac.uk/15284/.
Full textXia, Tian. "INVESTIGATION OF DRILLING PERFORMANCE IN CRYOGENIC DRILLING ON CFRP COMPOSITE LAMINATES." UKnowledge, 2014. http://uknowledge.uky.edu/me_etds/36.
Full textŠvec, Michal. "Silové zatížení frézovacích nástrojů při obrábění." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2020. http://www.nusl.cz/ntk/nusl-417539.
Full textHebditch, Max. "Computational modelling approaches for studying protein-protein and protein-solvent interactions in biopharmaceuticals." Thesis, University of Manchester, 2018. https://www.research.manchester.ac.uk/portal/en/theses/computational-modelling-approaches-for-studying-proteinprotein-and-proteinsolvent-interactions-in-biopharmaceuticals(b965e1ee-0769-476c-970b-6c676468e577).html.
Full textJiao, Feifei. "Investigation on micro-cutting mechanics with application to micro-milling." Thesis, Brunel University, 2015. http://bura.brunel.ac.uk/handle/2438/12066.
Full textAbebe, Abay Damte, and Qikang He. "Foam Behavior Analysis Based On A Force Measurement System." Thesis, Högskolan i Halmstad, Akademin för ekonomi, teknik och naturvetenskap, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-37250.
Full textCai, Shaobiao. "3D numerical modeling of dry/wet contact mechanics for rough, multilayered elastic-plastic solid surfaces and effects of hydrophilicity/hydrophobicity during separation with applications." Columbus, Ohio : Ohio State University, 2008. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1205118488.
Full textHahlin, Mattias. "Evaluation of variations of the frictional force between a bullet and a case in a loaded cartridge." Thesis, Karlstads universitet, Fakulteten för hälsa, natur- och teknikvetenskap (from 2013), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-68653.
Full textKull, Neto Henrique 1988. "Uma contribuição ao estudo do fresamento de liga de titânio : vida de ferramenta, forças de corte e rugosidade da peça." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263046.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-22T01:55:03Z (GMT). No. of bitstreams: 1 KullNeto_Henrique_M.pdf: 6161142 bytes, checksum: 4f755b77cb291982660eff8091931b82 (MD5) Previous issue date: 2013
Resumo: O titânio e suas ligas são considerados materiais de baixa usinabilidade devido a diversas propriedades inerentes ao material. Dentre elas pode-se citar a alta resistência mecânica em altas temperaturas, a baixa condutividade térmica, a alta reatividade química com os materiais de ferramentas e o baixo módulo de elasticidade (que é um fator incentivador de vibrações). Devido à alta tendência à vibração que a usinagem (principalmente o fresamento) de titânio tem para se usinar da maneira mais produtiva possível ligas de titânio, há que se lidar com a vibração da ferramenta e/ou da peça. O presente trabalho busca aprofundar o estudo do fresamento frontal da liga Ti-6Al-4V, tendo como objetivos: encontrar material de haste da ferramenta que diminua a vibração no processo de usinagem, para com isso aumentar a vida da ferramenta de corte, e encontrar condições de usinagem (velocidade de corte e avanço por dente) que proporcionem maior vida da ferramenta. As hastes de aço furada e preenchida com poliuretano proporcionaram aumento da frequência natural do porta-ferramentas. Entretanto, foi verificada uma redução da rigidez do porta-ferramentas, que gerou grande variação dos esforços de corte e maior carregamento radial. Os resultados mostraram que quando se utiliza baixas rotações, portanto baixa frequência de entrada de dentes, a deflexão da ferramenta passa a ser o fator de maior contribuição para o fim de vida da ferramenta e, portanto, as hastes de aço furada e preenchida com poliuretano proporcionaram menores vidas da ferramenta que as hastes comerciais de aço maciça e de metal duro. O principal mecanismo de desgaste verificado em todos os testes foi o attrition, com microlascamento da aresta de corte. Quando se verificou a influência da velocidade de corte, do avanço por dente e do material da haste da fresa (aço ou metal duro) na vida da fresa medida em volume de cavaco removido por aresta, constatou-se que o único parâmetro que influenciou a vida da ferramenta foi à velocidade de corte
Abstract: Titanium and its alloys are known as difficult to machine materials because of their unique combination of properties, such as high strength at elevated temperatures, low thermal conductivity, high chemical reactivity with almost all tool materials and low modulus of elasticity (which favors vibration). Because of the high tendency of vibration in titanium milling, it is necessary to keep vibration under control in order to achieve high productivity. This work focused on the study of tool life, cutting forces and work piece roughness in the end milling of Ti-6Al-4V alloy. The main objectives were to find a tool holder material that provides reduction of vibration in the milling process, increasing tool life, and to find cutting parameters (cutting speed and feed per tooth) that provide longer tool lives. The bored tool holder and the tool holder filled with polyurethane exhibited higher natural frequency. However, it was noticed a decrease in the tool holder stiffness, which caused variation of cutting force and higher axial load. Results showed that at low cutting speeds (with low cutting frequency), tool holder deflection is the main factor affecting tool life and, therefore, the bored and the polyurethane filled tool holders generated shorter tool lives than the commercial tool holders of steel and cemented carbide. Attrition was the main wear mechanism in all tests. The influence of cutting speed, feed per tooth and tool holder material (steel and cemented carbide) on the tool life (measured in terms of volume of chip removed per cutting edge) was analyzed. It could be seen that the only parameter which had any influence on tool life was the cutting speed
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
中本, 剛., Takeshi NAKAMOTO, 英二 社本, Eiji SHAMOTO, 義丈 山崎, Yoshitake YAMAZAKI, 洋一 白形, and Youichi SHIRAKATA. "レーザー焼結によるホウ化チタン砥石の開発 (ホウ化チタン成膜と研削性能の基礎研究)." 日本機械学会, 2006. http://hdl.handle.net/2237/9004.
Full textManarelli, Flávio Henrique. "Estudo do desgaste das ferramentas no microfresamento frontal." Ilha Solteira, 2018. http://hdl.handle.net/11449/157492.
Full textResumo: A microusinagem é um dos processos de fabricação capaz de produzir produtos ou geometrias de precisão e complexidade com detalhes menores que 1 mm. Contudo, para um melhor desempenho do processo de usinagem associado à qualidade do produto, entender a interação peça-ferramenta é fundamental. Esta pesquisa determinou a influência do tipo de corte e do avanço da ferramenta no desgaste da fresa (ferramenta), na energia específica de corte (processo) e na rugosidade (peça), ao empregar a operação de microfresamento de topo no aço COS AR60 de grãos ultrafinos. Os ensaios foram realizados em um centro de usinagem Romi D600 com a adaptação de um cabeçote de alta rotação (60 krpm) sem aplicação de fluido de corte. Microfresas de topo reto (Ø 800 µm) com substrato de metal duro e revestidas com TiAlN foram aplicadas nos testes. A profundidade de usinagem e a velocidade de corte foram mantidas constantes em 160 µm e 60 m/min, respectivamente. Foram variados o avanço por dente (3 e 10 µm/z) e o tipo de corte (simétrico em cheio e em face e assimétrico concordante e discordante). Análise de Variância (ANOVA) com intervalo de confiança de 95% foi aplicada a cada uma das três réplicas. Os resultados indicaram que os níveis de desgaste e a redução do diâmetro da microfresa são influenciados pelo avanço da ferramenta e tipo de corte. As maiores reduções no diâmetro (≈11%) foram devido ao impacto periódico da aresta de corte na peça e não pelo efeito de sulcamento (≈4%). Além disso, para o pe... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Micro-machining is one of the processes feasible for generating geometries or parts with precision and complexity regarding dimensions smaller than 1 mm. However, the achievement of enhanced machining performance and product quality requires a prior understanding on the tool-workpiece interface. This research detemined the influence of cutting type and cutting feed on wear (tool), specific cutting force (process) and surface roughness (workpiece) when cutting the ultrafine-grained steel COS AR60 under end milling strategy. Machining tests were performed in a CNC machining centre Romi D600 provided with a high-speed spindle (60kpm) without cutting fluid application. TiAlN coated carbide endmill (Ø 800 μm) was used for straight cut with 60 m/min cutting speed, 160 μm depth of cut and feed per tooth of 3 and 10 μm. Analysis of Variance (ANOVA) with confidence interval of 95% was applied to the three runs of each cutting sets. The results have shown that tool wear levels and tool effective diameter are influenced by tool feed and cutting type. Hence, intermittent impact of tool’s cutting edges into the workpiece (≈11%) during cutting revealed to be the major cause of tool wear when compared to cutting mechanism dominated by ploughing (≈4%). Regarding experimental sets with cutting length of 98,018 m there was a predominance of tool edge chipping over abrasion and adhesion when performing face cutting with ploughing at 4.2%. On the other hand, if ploughing increases to 14.3% the m... (Complete abstract click electronic access below)
Mestre
Živko, Pavlović. "Karakterizacija površinske strukture neštampajućih elemenata CtP termalne štamparske forme za ofset štampu." Phd thesis, Univerzitet u Novom Sadu, Fakultet tehničkih nauka u Novom Sadu, 2012. http://dx.doi.org/10.2298/NS20120519PAVLOVIC.
Full textDissertation gives an overview of the current state, research and theories ofprinting forms and influence of printing process on wearing of non-printingelements within the science community. The dissertation points out the continuousmonitoring of topographic changes of printing form non-printing elements to controlthe exploitation of a period of time and the process of reproduction. This workcontributes to new research with the analysis of large number of experimentalsamples and calculated correlations and represents an advance in thecomprehension of the surface wear mechanism of printing form non-printingelements and their influence on the tribological changes to the structure of thebase layer of aluminium and aluminium oxide.
Mandard, Romain Baptiste. "Dynamique de contact aube- revêtement abradable : identification expérimentale de la force et des mécanismes d'interaction." Thesis, Ecole centrale de Lille, 2015. http://www.theses.fr/2015ECLI0001.
Full textMinimizing the clearance between turbofan blades and the surrounding casing is a key factor to re-ducing leakage flows and consequently improving efficiency. The tight clearance may lead to blade-casing interactions. An abradable coating is deposited on the casing to accommodate blade incursions and thus to protect the blades and the casing from severe damage. Blade/abradable-coating interactions involve tribological and vibratory phenomena at high velocity and temperature. Experimental knowledge of these interactions is paramount to the proper design of abradable materials and the prediction of their lifetimes through numerical simulations. The purpose of this thesis is to identify experimentally the force and the mechanisms occuring during interaction between a vibrating blade and an AlSi-Polyester abradable coating. To this end, experiments were conducted on a dedicated test rig, in conditions representative of low-pressure compressor situation. Specific methods involving dynamical measurements and analytical models have been developed in order to obtain the blade/abradable-coating interacting force as well as the blade tip incursion. The influence of temperature, coating nature and blade stiffness has been studied. The interaction mechanisms and wear of the abradable coating have been investigated and correlated with the interaction conditions. This work was achieved within the framework of cooperation between Laboratoire de Mécanique de Lille (France), SAFRAN-SNECMA (France) and ONERA, the French Aerospace Lab
Ferreira, Mauro Fernando. "Influência da soldagem de revestimento na vida útil de ponteiras sulcadoras de semeadoras adubadoras." Universidade Federal de Pelotas, 2008. http://repositorio.ufpel.edu.br/handle/ri/1168.
Full textThis work had as objective to analyze alternatives to increase the useful life of the ferrules of hoe opener rods of no-till planters, through the addition of covering welding. It was verified the performance of five welding types, being used covered electrodes and tubular wire, over the extremity of the hoe. The tests were executed in franc-sandy soil characterized physically by its texture, plasticity index, density, and water tenor, as well as the resistance to the penetration. The wearing, the horizontal and vertical force were obtained in intervals of 10,5km to the limit of 52,5km. The results indicated that the witness ferrule has lost in the average of the experiment 38,41% of its initial mass when it traveled 52,5km while the other welded ferrules traveled between 61,0km and 108,7km to reach the same mass reductions. It was observed that the vertical and horizontal forces contributed with 11% and 89%, respectively, of the resulting force in the hoe. With the use of the coverings, it was obtained an increase of the area worked in the sowing, for the largest durability of the tools, between 2,0ha and 13,4ha, in relation to the witness. The theoretical field efficiency was larger when it was used the coverings. The tubular wire increased in 5,1% in relation to the ferrule without covering. Starting from the found results we can conclude that it is possible to increase the useful life of the ferrules of furrow opener rods through the addition of welding material and that the conservation of the geometry of the tools, provides the maintenance of the forces that have action on these ones as well as their functional characteristics.
Este trabalho teve como objetivo analisar alternativas para o aumento da vida útil das ponteiras de hastes sulcadoras de semeadoras adubadoras, através da adição de soldagem de revestimento. Verificou-se o desempenho de cinco tipos de soldagem, utilizando-se eletrodos revestidos e arame tubular, sobre a extremidade das ponteiras. Os testes foram executados em solo franco-arenoso caracterizado fisicamente pela sua textura, índice de plasticidade, densidade e teor de água, assim como a resistência à penetração. O desgaste, a força horizontal e vertical foram obtidos em intervalos de 10,5km até o limite de 52,5km. Os resultados indicaram que a ponteira testemunha perdeu na média do experimento 38,41% da sua massa inicial quando percorreu 52,5km enquanto que as demais ponteiras soldadas percorreram entre 61,0km e 108,7km para atingir as mesmas reduções de massa. Observou-se que as forças verticais e horizontais contribuíram com 11% e 89%, respectivamente, da força resultante na ponteira. Com o uso dos revestimentos obteve-se um aumento da área trabalhada na semeadura, pela maior durabilidade das ferramentas, entre 2,0ha e 13,4ha, em relação à testemunha. A eficiência de campo teórica foi maior quando se utilizou os revestimentos sendo que o arame tubular aumentou em 5,1% em relação à ponteira sem revestimento. A partir dos resultados encontrados conclui-se que se pode aumentar a vida útil das ponteiras de hastes sulcadoras através da adição de material soldável e que a conservação da geometria das ferramentas, proporciona a manutenção das forças atuantes sobre estas assim como a suas características funcionais.
Hassaini, Roumaissa. "Etude de la turbulence d'ondes élastiques et gravito-capillaires : de l'idéal théorique aux conditions réelles ?" Thesis, Université Grenoble Alpes (ComUE), 2018. http://www.theses.fr/2018GREAI064/document.
Full textWeak wave turbulence (WTT) is a statistical theory applied to a large number of incoherent and dispersive waves. Based on the hypothesis of small non-linearity and infinite domain the theory predicts an energy cascade from the forcing scales to the dissipative scales. The confrontation of WTT to experiment for surface waves raises many inconsistencies. The strong hypotheses on which is developed the WWT may be the explanation of such disparity between experiment and theory. The aim of this Thesis is to investigate the impact of the invalidation of some of these conditions on the statistical properties of turbulence. Experiments of interfacial waves between two non-miscible fluids with different viscosities have been carried out to characterize the effect of the increase of viscous dissipation on the energy cascade. An experiment at the surface of water with an increasing confinement of the width of the vessel has been done in order to possibly observe a co-existence between discrete turbulence and classical turbulence. An experimental study of gravity-capillary waves with a decrease of dispersion led us to the observation of a transition to a solitonic regime. In order to verify whether such a transition can be observed in a different physical system, an experimental and numerical study were conducted on the waves in a prestressed elastic plate. In this medium, the effect of dispersion of bending waves is competing with the non-dispersive aspect of stretching waves. We also studied weakly and strongly non-linear regimes of purely stretching waves in a membrane
Flodr, Vojtěch. "Testování řezných nástrojů povlakovaných nanokrystalickými kompozity." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228891.
Full textÅkerman, Jonas. "Extensions in Flux : An Essay on Vagueness and Context Sensitivity." Doctoral thesis, Stockholms universitet, Filosofiska institutionen, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-30080.
Full textAntonialli, Armando Italo Sette. "Uma contribuição ao fresamento frontal da liga de titanio Ti-6Al-4V." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264153.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: As ligas de titânio apresentam baixa usinabilidade devido à reduzida condutividade térmica, à manutenção de suas propriedades mecânicas em altas temperaturas, à elevada afinidade química com os materiais de ferramentas e ao baixo módulo de elasticidade. Esta última característica promove instabilidade da espessura de corte, o que se traduz em altos níveis de vibração, especialmente em processos de usinagem caracterizados por corte interrompido. Este trabalho trata da otimização do fresamento frontal da liga de titânio Ti-6Al-4V a partir da minimização da vibração da ferramenta através de variações do ângulo de posição da ferramenta e do ângulo de contato entre o inserto e o corpo de prova. Os resultados mostram que a utilização de um ângulo de posição reduzido prolonga a vida da ferramenta por associar a maior parte do carregamento radial a freqüências muito baixas, nas quais a ferramenta se comporta como um corpo rígido. O emprego de um ângulo de contato reduzido, por outro lado, é extremamente danoso à vida da ferramenta, pois a entrada do inserto no corpo de prova se dá em condições adversas. Attrition seguido de microlascamentos da aresta, nas condições em que houve vibração excessiva ou intenso choque na entrada do inserto, e difusão, nas condições dinamicamente mais estáveis, foram os principais mecanismos de desgaste de ferramenta verificados neste trabalho
Abstract: Titanium alloys present poor machinability because of their low thermal conductivity, their ability to keep good mechanical properties at high temperatures, their high chemical affinity to tool materials and their low Young modulus. This last characteristic generates instabilities of cutting thickness, which means high vibration levels, especially in machining processes involving interrupted cutting. This work studies Ti-6Al-4V titanium alloy face milling optimization by tool vibration reduction using different tool entering angles and different radial immersion angles between tool and workpiece. Results show that using low entering angle do extends tool life due to associating most radial load with very low frequencies, in which tool behaves like a rigid body. On the other hand, using low radial immersion angle extremely impairs tool life, as tool insert enters the workpiece on adverse conditions. Attrition followed by cutting edge microchipping, on experiments in which high vibration levels or intense shock on tool insert enter where found, and diffusion, on experiments dynamically more stable, were the main tool wear mechanisms observed in this work
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
Pires, Bruno Jorge. "Estudo das forças, vibrações e desgaste das ferramentas no fresamento da liga de titânio Ti-6A1-4V." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264148.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Ligas de titânio já apresentam um papel de grande importância na indústria aeroespacial, petroquímica e de biomateriais. A combinação de alta resistência mecânica, baixa densidade, resistência à corrosão, biocompatibilidade, boa tolerância tecidual e manutenção de suas características em altas temperaturas, configuram o titânio como um material excepcional para projetistas de diversas áreas. Infelizmente, estas boas qualidades não se refletem na sua usinabilidade. Uma vasta lista de problemas devem ser contornados durante a usinagem de ligas de titânio dentre os quais, altas temperaturas e pressões de corte, baixo módulo de elasticidade (incentivador de vibrações), alta afinidade química com os materiais das ferramentas e problemas com integridade superficial das peças usinadas. Com o objetivo de aprimorar o entendimento da usinagem de ligas de titânio, em especial do processo de fresamento frontal da liga Ti-6Al-4V, o presente trabalho teve como enfoque tecnológico a influência do material do porta-ferramenta (haste de aço e de metal duro) e a geometria do inserto de corte (ângulo de saída neutro e positivo) sobre a vida da ferramenta e forças de usinagem (Força Radial, Tangencial e Axial). Análises de espectrometria de energia dispersiva foram conduzidas a partir de microscopia eletrônica dos insertos desgastados, permitindo a identificação dos elementos químicos presentes e avaliação dos mecanismos de desgaste predominantes. O principal resultado obtido indica que a utilização de ferramentas com haste de metal duro não representou benefícios em termo de vida da ferramenta, apresentando desempenho muito próximo das ferramentas com haste de aço
Abstract: Titanium alloys play a major role in the aerospace, petrochemical and biomaterials industry. The combination of mechanical strength, low density, corrosion resistance, biocompatibility and maintenance of these characteristics at high temperatures, shape titanium as a exceptional material for designers from different areas. Unfortunately, these impressive qualities reflect negatively on its machinability. A substantial list of problems must be overcome during the machining of titanium alloys, among them high temperatures and pressures of cut, low elasticity modulus (which is a motivational factor for vibrations), high chemical affinity with almost all tools materials and problems with surface integrity of machined parts. In order to improve the understanding of titanium alloys machining, in particular front milling of Ti-6Al-4V, the present thesis focused the influence of the tool holder material (steel and carbide) and the cutting insert geometry (neutral and positive rake angle) on the tool life and machining forces (Radial, Axial and Tangencial Forces). Analysis of energy dispersive spectroscopy were also conducted from scanning electron microscopy of wear inserts, allowing the identification of chemical elements and evaluation of wear mechanisms predominate. The main result indicates that the use of carbide tool holders not represent benefits in terms of life tool, with performance very close to the steel tool holders
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
Čejka, Libor. "Produktivní obrábění titanových slitin." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230589.
Full textAxmanová, Hana. "Moderní řezné nástroje pro zapichování a upichování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2013. http://www.nusl.cz/ntk/nusl-230619.
Full textLe, Mercier Kévin. "Stratégie numérique et expérimentale pour la maîtrise des dégradations des outillages en mise en forme à froid." Thesis, Valenciennes, 2017. http://www.theses.fr/2017VALE0007/document.
Full textCold forming of aluminium alloys can be limited by a severe material transfer to the die surfaces, compromising the process viability. The purpose of this research work is to contribute to a broader understanding of the galling mechanisms which would further allow the optimisation of the forming processes of an Al-Mg-Si alloy. A methodology combining experimental and numerical approaches is introduced in order to build up a database of surface degradations indicators. The experimental approach is carried out by means of upsetting-sliding tests which reproduce a wide range of contact conditions experienced at the tool/workpiece interface during cold forming operations. To evaluate the amounts of adhered material on the tools of each test configuration, surface topography acquisitions are performed by optical profilometry and coupled to scanning electron microscope analyses. Axisymmetric compression tests are carried out by means of the GLEEBLE 3500 thermomechanical simulator to determine the deformation behaviour of the Al-Mg-Si alloy at high strains, in the temperature range of 298 to 423 K and strain rates of 0.1 and 1 s¡1. A constitutive model based on both the Mechanical Threshold Stress model and the analysis of the work-hardening rate is proposed and then implemented in a finite element code. A finite element simulation of the upsetting-sliding test, which is a thermomechanical analysis using the arbitrary lagrangian-eulerian formulation, is introduced. The local contact variables such as the contact pressure and the sliding velocity are evaluated through this simulation and allow a better understanding of the galling mechanisms observed experimentally. Finally, a post-processing program, which analyses the results of the finite element simulation and updates the tool shape according to the amount of adhered material determined experimentally, is developed. A wear model based on the friction work is introduced. This model is a good indicator of the galling tendency and allows a first approximation of this mechanism
Marc, Estelle. "Analyse de la réponse tribologique d'un contact cylindre/plan soumis à des sollicitations de fretting sous chargement complexe : influence d'une solution Lithium-Bore." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC001/document.
Full textThis PhD thesis presents an analysis of the fretting wear of a cylinder/plane contact subject to complex loading conditions, namely a normal sinusoidal force solicitation and a tangential sinusoidal displacement, both possibly subject to fluctuations in amplitude, frequency and phase shift between signals. The purpose of this work is to study the wear of 304L cluster guides by nitrided 316L rods due to flow-induced vibrations of primary fluid in nuclear reactors.Firstly, the experimental study conducted in a dry and ambient temperature - a non-representative but very simple environment - shows significant wear of both counter-bodies, which reveals the fragile properties of the nitrided tube in this environment. A very strong dependence of the fretting scar morphology with the sliding amplitude is noted. Only the wear kinetics of the nitrided tube is influenced by the evolution of the normal load. Also, an analytical description of friction energy is developed, taking into account all loading parameters.In a second hand, in aqueous lithium-boron solution, a slightly more representative choice of medium but still remaining in the ambient, only the 304L steel plane wears out, the 316L nitrided steel cylinder is not subject to detectable wear. A coupling with corrosive phenomena is proposed. In simple fretting, contact confinement locally increases the pH value. Moreover, the analysis of the influence of the fretting frequency suggests that only the passive layer is worn between each slip. Under complex loading, the fluctuation of the normal load allows a better accessibility of the solution in the rubbed interface, increasing locally the tribocorrosive effects. A multiplicative wear law taking into account the various effects of normal force fluctuation is introduced and its stability is checked.Finally a finite element calculation model is used to simulate wear profiles in simple fretting and also in the presence of variable normal force. Only cases where the plan wears out (lithium-boron environment) have been simulated. In simple fretting, test simulation results are satisfactory. On the other hand, the non-superposition of the experimental and numerical profiles when the normal force fluctuates, confirms the presence of physical phenomena in the interface which are not yet represented in the numerical tool