Dissertations / Theses on the topic 'Stresses and deformations condition'
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Rousseau, Carl Q. "Stresses and deformations in angle-ply composite tubes." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/51901.
Full textMaster of Science
Shah, Ketan R. Carleton University Dissertation Engineering Civil. "Deformations and stresses in pipelines buried in freezing ground." Ottawa, 1990.
Find full textMassicotte, Daniel. "Finite element calculations of stresses and deformations in buried flexible pipes." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0018/MQ57140.pdf.
Full textKennedy, Kevin Francis. "A method for metal deformation and stress analysis in rolling." Connect to resource, 1986. http://rave.ohiolink.edu/etdc/view.cgi?acc%5Fnum=osu1261418472.
Full textKhoun, Karine. "Process-induced stresses and deformations in woven composites manufactured by Resin Transfer Moulding." Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=66887.
Full textCe travail étudie les facteurs conduisant au développement de contraintes et déformations résiduelles induites par le procédé d'injection sur renforts dans le cas de composites à renforts tissés. Les mécanismes intrinsèques ainsi qu'extrinsèques ont été pris en considération. Tout d'abord, une méthodologie a été utilisée pour caractériser les propriétés thermo-chimiques et thermo-mécaniques de la résine époxy CYCOM 890RTM. Le développement de modèles mathématiques pour décrire les différentes propriétés est une étape essentielle pour comprendre clairement l'évolution du comportement de la résine lors du procédé de fabrication. Ensuite, les propriétés thermo-mécaniques d'un tissu satin de 5 ont été examinées en utilisant une approche de micromécanique sur un motif élémentaire. Différentes fractions volumiques de fibre entre 50% et 62%, correspondant aux fractions volumiques de fibre typiquement utilisées pour le procédé d'injection sur renfort, ont été étudiées. Les propriétés ont été comparées aux propriétés obtenues pour des laminés unidirectionnels croisés équivalents. En général, les propriétés des deux configurations sont comparables. Ceci justifie l'utilisation des propriétés de fibre unidirectionnelle dans une configuration croisée pour simuler le comportement d'un laminé à renfort tissé satin de 5. Les modèles des propriétés de la résine et des fibres ont été ensuite implémentés dans un logiciel d'éléments finis, ABAQUS/COMPRO, afin de prédire l'évolution des propriétés du laminé pendant le procédé d'injection sur renforts. Des fibres optiques à réseaux de Bragg ont été également utilisées pour caractériser expérimentalement les interactions entre le composite et le moule générées pendant le procédé. Les fibres optiques saisirent la séparation entre le composite et le moule pendant le refroidissement. La contrainte
Cooper, David E. (David Edward). "Stresses and deformations in cross-ply composite tubes subjected to circumferential temperature gradients." Thesis, Virginia Tech, 1985. http://hdl.handle.net/10919/45556.
Full textThe stresses and deformations in cross-ply composite tubes subjected in circumferential temperature gradients are studied. The motivation behind the study is the anticipated use of composite tubes in space structures where the tube is exposed to the heat of the sun on one side and the cryogenic temperatures of space on the other. Experiments were performed to measure the functional form of the temperature gradient and the displacements. It was found that the form of the temperature gradient, T(Ɵ), can accurately be represented by T(Ɵ) = A + BcosƟ¸ and that the displacement of the tube is parabolic in the axial coordinate. Two types of analytical solutions were developed: an exact elasticity U solution and an approximate solution. The approximate solution includes a linear variation of the material properties with temperature and uses the principle of complementary virtual work in conjunction with a Ritz approximation on the stress field. The elasticity solution predicts that high tensile stresses could crack the matrix. The effect of including temperature-dependent material properties is to reduce the circumferential dependency of the stresses.
Master of Science
Lindgren, Lars-Erik. "Deformations and stresses in butt-welding of plates : numerical simulation and experimental verification." Doctoral thesis, Luleå tekniska universitet, Material- och solidmekanik, 1985. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26528.
Full textGodkänd; 1985; 20070424 (ysko)
Arafath, Abdul Rahim Ahamed. "Efficient numerical techniques for predicting process-induced stresses and deformations in composite structures." Thesis, University of British Columbia, 2007. http://hdl.handle.net/2429/30707.
Full textApplied Science, Faculty of
Civil Engineering, Department of
Graduate
Bowles, David Earl. "Micromechanics analysis of space simulated thermal deformations and stresses in continuous fiber reinforced composites." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54496.
Full textPh. D.
Lin, Yi Han. "A mathematical theory of elastic orthotropic plates in plane strain and axi-symmetric deformations." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/27436.
Full textScience, Faculty of
Mathematics, Department of
Graduate
Udakara, Deepthi De Silva. "Experimental study of a modified flat dilatometer under plane strain condition." Thesis, Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22089007.
Full textJetchick, Elizabeth. "Stress, deformation and micromorphological aspects of soil freezing under laboratory conditions." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0001/NQ32336.pdf.
Full textAves, Peter Charles. "Mechanics of compaction and dilatancy in triaxilly stressed rocks, under simulated crustal conditions, studied by pore volumometry." Thesis, University College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.362379.
Full textFeng, Ping. "Deformation instability and morphology in shape memory alloy under stress /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?MECH%202005%20FENG.
Full textSjödin, Johan. "Steel-to-timber dowel joints : Influence of moisture induced stresses." Licentiate thesis, Växjö University, School of Technology and Design, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:vxu:diva-1286.
Full textJoints are critical parts of timber structures, transmitting static and dynamic forces between structural members. The ultimate behavior of a loaded building depends strongly on the structural configuration and the capacity of the joints. The collapse of a whole building or less extensive accidents that may occur is usually starting as a local failure inside or in the vicinity of a joint. Such serious failures have recently occurred in our Nordic countries. Especially the collapse of two large glued laminated timber structures clearly indicates the need of an improved joint design. The trend toward larger and more complex structures even further increases the importance of a safer design of the joints.
An aim of this partly experimental and partly numerically based thesis has been to investigate if steel-to-timber dowel joints are affected by moisture-induced stresses. The experimental results showed that the load-bearing capacity of the joints is reduced by such a moisture influence. Most of the decrease in load-bearing capacity observed was found in joints initially exposed to restrained shrinkage deformations caused by the presence of dowel fasteners in the joint area. The load-bearing capacity was, however, also found to decrease in joints exposed to an initial decrease in moisture without any fasteners present in the specimens during storage before loading. An explanation of this unexpected behavior is that moisture gradients cause tensile stresses. It is shown by numerical simulations that the moisture-induced stresses are so large that they may have a considerable influence on the joint behavior.
Use of contact-free measurement methods, used in some of the experimental tests, was in many ways found to be superior to traditional measurement techniques, but was also found to be a valuable complement to the numerical analysis performed. From numerical results obtained in combination with results from contact-free measurements several observations of considerable interest were made. For dowel-type joints loaded in tension parallel to the grain a strongly non-uniform strain distribution was found in the joint area. It was further observed that the shear and tensile strains were concentrated close to the fasteners in the joint area. These concentrations will influence the failure mode of the joint. A general observation was that the larger sized joints failed in a brittle manner.
Keywords: constraint stresses, contact-free measurement, dowel-type joints, humidity variations, moisture-induced deformations, timber structures
Elfving, Filip. "Simulation of laser welding in sandwich rocket nozzle." Thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-36830.
Full textLeung, Ho Yee. "The anisotropic small strain stiffness of completely decomposed tuff and its effects on deformations associated with excavations /." View abstract or full-text, 2005. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202005%20LEUNG.
Full textHilson, Gabrielle De Backer. "The inter-relationship between surface condition and near surface residual stresses in engineering components." Thesis, University of Bristol, 2008. http://hdl.handle.net/1983/7abb1970-46af-4b2b-839b-b78fb098f381.
Full textBrocka, Christopher G. "Laramide stress conditions and deformation mechanisms during the formation of Derby and Dallas Domes, Weiser Pass Quadrangle, Wind River Mountains, Wyoming." Diss., Columbia, Mo. : University of Missouri-Columbia, 2007. http://hdl.handle.net/10355/4922.
Full textThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on April 15, 2009) Includes bibliographical references.
Nguyen, Vu Thua 1965. "Prediction of spring-back in thin sheet of aluminium alloy." Monash University, School of Physics and Materials Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5855.
Full textXin, Xudong. "An analytical and numerical analysis of dynamic failure based on the multi-physics involved /." free to MU campus, to others for purchase, 2001. http://wwwlib.umi.com/cr/mo/fullcit?p3025668.
Full textZhang, Zhiming. "An Integrated System for Road Condition and Weigh-in-Motion Measurements using In-Pavement Strain Sensors." Diss., North Dakota State University, 2016. http://hdl.handle.net/10365/25819.
Full textUSDOT (U.S. Department of Transportation)
MPC (Mountain-Plains Consortium)
Luo, Gang Liu Mian. "Dynamic links between short-term deformation and long-term tectonics a finite element study /." Diss., Columbia, Mo. : University of Missouri--Columbia, 2009. http://hdl.handle.net/10355/6966.
Full textBranch, D. G. "Study of mine tunnel stability with reference to stress conditions and deformational response of associated carboniferous rocks." Thesis, University of Nottingham, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.378763.
Full textClements, James Wesley. "Laramide stress conditions and deformations mechanisms during the formation of Hudson and Dallas Domes, Lander Quadrangle, Wind River Mountains, Lander, Wyoming." Diss., Columbia, Mo. : University of Missouri-Columbia, 2008. http://hdl.handle.net/10355/5640.
Full textThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file and four media files (media file 1.pdf, media file 2.pdf, media file 3.pdf, and media file 4.pdf) Title from title screen of research.pdf file (viewed on August 25, 2008) Vita. Includes bibliographical references.
Shen, Kai, and 沈凱. "A transmission electron microscopy study of the development of rollingdeformation microstructures in an interstitial free steel." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B31245894.
Full textKukiełka, Krzysztof. "Modeling and numerical analysis of the states of deformations and stresses in the surface layer of the trapezoidal and round threads rolled on cold : PhD thesis summary." Rozprawa doktorska, [s.n.], 2008. http://dlibra.tu.koszalin.pl/Content/1110.
Full textForysewicz, Monika. "Analysis of the deformation and stress condition in the visco-elastic-plastic materials processing area during a high-speed single-blade cutting : PhD thesis summary : [synopsis]." Rozprawa doktorska, [s.n.], 2015. http://dlibra.tu.koszalin.pl/Content/1058.
Full textSantos, Cleudiane Soares 1979. "Proposta de sistema automatizado para Medição de tensão utilizando o efeito acustoelástico." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/264007.
Full textTese (doutorado) ¿ Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Sistemas automatizados vêm sendo desenvolvidos e empregados a fim de melhorar a qualidade de medição, minimizar custo e o tempo empregados nas inspeções industriais. Este trabalho descreve o desenvolvimento de um sistema automatizado para medições de tensões utilizando ultrassom. Nele estão detalhadas as características técnicas, os componentes necessários, as vantagens e as dificuldades do sistema. Tal sistema permite a avaliação do componente com tempo reduzido, baixo custo e confiabilidade. A metodologia proposta utiliza o efeito acustoelástico com ondas longitudinais criticamente refratadas (Lcr) para determinar a tensão no material. Foi projetado e construído o protótipo de um robô capaz de permitir rapidez e objetividade ao processo de medição, além de se adaptar a diâmetro de dutos, em uma ampla faixa. Os resultados obtidos para o tempo de percurso das ondas Lcr foram comparados com outros métodos de obtenção da tensão: analítico teórico, método de elementos finitos, extensometria e calculado usando o tempo de percurso das ondas Lcr. Os resultados finais da tese mostram que o dispositivo automatizado pode ser empregado na avaliação de tensões em dutos petrolíferos, atingindo o objetivo principal do trabalho, representando um avanço e contribuindo para o aprimoramento das técnicas de inspeção e monitoramento da saúde estrutural de componentes
Abstract: Automated systems have been developed and used to improve the measurement quality, minimizing cost and time employed in industrial inspection. This thesis describes the development of an automated system for measuring stress using ultrasound. The technical features and the necessary components of the system are detailed, as well its advantages and difficulties of implementation. Such a system allows the evaluation of the component with short time, low cost and reliability. The proposed methodology uses the acoustoelastic effect with critically refracted longitudinal waves (Lcr) to determine the stress in the material. It was designed and built a prototype robot that can provide speed and objectivity to the measurement process and adaptation to a wide range of duct diameters. The results for the travel time of the Lcr waves were compared with other methods of obtaining the stress: analytical theory, finite element method, strain gages and calculated using the travel time of the Lcr waves. The final results of the thesis show that the device can be used in automated assessment of stress in oil pipelines, reaching the main objective, representing a breakthrough and contributing to the improvement of technical inspection and health monitoring of structural components
Doutorado
Mecanica dos Sólidos e Projeto Mecanico
Doutora em Engenharia Mecânica
Rogačius, Ričardas. "Marijampolės, Vilkaviškio, Šakių ir Kėdainių rajonų slenkstinių pralaidų būklės kitimo analizė." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2012. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2012~D_20120530_125034-24410.
Full textMost hydraulic structures are used by more than 30 years. Practically every building is of reinforced concrete structures. Reinforced concrete is a durable material, but eventually for various reasons (natural aging of materials, loading and various factors: the mechanical, physical, chemical, specific) changes occur in the structures made of these materials worsening usage properties of the structure, shortening the life span. Concrete and reinforced concrete degradation processes are very complicated because a variety of factors that change the physical and mechanical properties operate at the same time. Therefore, the durability of structures depends on the intensity of decomposition processes. Essential requirements of structural stability are presented in the construction regulation STR 1.12.05:2010. The aim of the research was to investigate, evaluate and compare condition of overflow spillways situated in Marijampolė, Šakiai, Vilkaviškis and Kėdainiai districts with previous results. During scientific expeditions in 2011 – 2012 the condition of ten overflow spillways were examined visually, their age is 50 – 60 years old, the oldest is 76 years old. Studying condition changes of the damages in overflow spillways the following structure diagnostic methods were used: Indoor works; Visual method; Non-destructive method for the determination of the strength of concrete (instrumental); The technical condition of overflow spillways was evaluated by scoring... [to full text]
Suzuki, Jorge Luis 1987. "Aplicação do método dos elementos finitos de alta ordem hp em hiperasticidade com dano isotrópico." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263518.
Full textDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
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Resumo: Este trabalho apresenta uma implementação em ambiente C++ da teoria do Dano em Meio Contínuo para hiperelasticidade sob regime compressível e quasi-incompressível. Para o caso quasi-incompressível, uma formulação mista (u=p) é tratada com um procedimento de projeção local da pressão hidrostática. O dano é um escalar que dependente da máxima deformação atingida. Para a validação dos métodos implementados, são realizados estudos de convergência através da imposição de soluções analíticas, variando a ordem de interpolação e o número de elementos. Também é analisado o comportamento da tensão através de ciclos de carregamento, para a observação da perda de rigidez progressiva sob os efeitos de dano. A formulação implementada contorna o problema de travamento de malha, sendo que de maneira geral, solução é melhor aproximada com o aumento do grau polinomial combinado com o aumento do número de elementos
Abstract: The objective of this work is the application of the high-order hpFEM to the analysis of hyperelastic materials coupled to isotropic damage. A mixed (u=p) formulation with a pressure projection procedure is used in conjunction with the hpFEM to overcome the volumetric locking. The isotropic damage model introduces a scalar variable that evolves coupled with the maximum attained strain. It is based on the equivalent stress concept, by applying a reduction factor over the stress tensor. A cyclic loading test was performed to reproduce the Mullins effect. Convergence analyses were made for a compressible and a quasi-incompressible material imposing analytical solutions. Both materials presented a spectral convergence rate for the p refinement using smooth solutions. In the case of quasi-incompressibility, the material showed locking-free characteristics, but the approximation errors were higher compared to the compressible case
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
Yu, Hao. "Modeling of High Strain Rate Compression of Austenitic Shape Memory Alloys." Thesis, University of North Texas, 2017. https://digital.library.unt.edu/ark:/67531/metadc1062835/.
Full textХаматов, Д. Д., and D. D. Khamatov. "Разработка и изучение нового способа накопления деформации применительно к технически чистому серебру : магистерская диссертация." Master's thesis, б. и, 2020. http://hdl.handle.net/10995/93992.
Full textThe objects of research are a wire billet made of ductile metal, as well as a method of accumulating plastic deformation in the winding operation. The purpose of this work is to develop and study a new method of accumulating plastic deformation by spiral bending of a wire blank made of commercially pure silver. A theoretical description of the spiral bending process is given. Work has been carried out to determine the mechanical properties of the processed material (in this case, silver of the Sr 99.99 brand). The results of physical modeling of the deformation accumulation process by a new method are described. A brief description of the QForm VX complex for mathematical modeling of metal forming processes is given. In the QForm VX modeling package, the problem of plastic deformation accumulation by spiral bending of a wire blank with subsequent straightening of the spiral was solved, and the calculation results are presented and analyzed.
Mikhaylenko, Maxim A. "Development and Application of the Boundary Singularity Method to the Problems of Hydrodynamic and Viscous Interaction." University of Akron / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1442423671.
Full textDarquennes, Aveline. "Comportement au jeune âge de bétons formulés à base de ciment au laitier de haut-fourneau en condition de déformations libre et restreinte." Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210239.
Full text1. Lors du suivi du retrait restreint à l’aide de l’essai à l’anneau en condition de dessiccation, le béton formulé à base de ciment au laitier de haut-fourneau a fissuré bien avant le béton formulé à base de ciment Portland.
2. Le retrait total en condition libre du béton formulé à base de ciment au laitier de haut-fourneau est nettement supérieur à celui du béton formulé à base de ciment Portland. Cette différence de comportement est principalement due à l’accroissement rapide et plus élevé du retrait endogène des bétons formulés à base de ciment au laitier de haut-fourneau.
Au vu de ces résultats expérimentaux, il a semblé intéressant de déterminer quel était l’impact de la déformation endogène des bétons formulés à base de ciments au laitier de haut-fourneau (CEM III) sur leur sensibilité à la fissuration. Afin de répondre à cette question, les déformations différées (retrait endogène, fluage propre en compression et en traction) au jeune âge de trois compositions de béton avec différentes teneurs en laitier (0, 42 et 71%) ont été étudiées expérimentalement en conditions libre et restreinte. Cependant, le suivi du retrait endogène libre et restreint a nécessité le développement de plusieurs dispositifs expérimentaux limitant au maximum les artefacts de mesure, tels que la TSTM (Temperature Stress Testing Machine). De plus, l’interprétation de ces résultats expérimentaux a également nécessité une caractérisation du comportement de ces matériaux à l’échelle macro- et microscopique.
Finalement, cette étude a montré que malgré une déformation endogène plus élevée, les bétons formulés à base de ciment au laitier de haut-fourneau fissurent après le béton formulé à base de ciment Portland. Ce comportement est dû à :
-l’impact du laitier sur la réaction d’hydratation du matériau cimentaire ;
-la présence d’une expansion de la matrice cimentaire des bétons formulés à base de ciment au laitier de haut-fourneau au jeune âge qui retarde l’apparition des contraintes de traction au sein du matériau ;
-la plus grande capacité de ces matériaux cimentaires à relaxer les contraintes de traction/
Today, the use of concretes with mineral additions (fly ash, slag) for civil engineering structures is spreading worldwide. Indeed, the production of blended cements is more respectful of the environment than the production of Portland cement, because it allows reducing greenhouse gas emissions and using industrial wastes. Slag cement concretes are also largely used for their good resistance to alkali-silica reactions, sulphate attacks and chloride diffusion. However, some of constructions built with slag cement concretes have exhibited cracking at early age due to their restrained deformations, such as thermal, autogenous and drying shrinkage. Following these observations, a preliminary experimental study was realized in the laboratory of BATir Department at ULB. It revealed several characteristics of the behaviour of slag cement concretes:
1. The study of restrained deformations under drying conditions by means of ring tests showed that the slag cement concretes seem more prone to crack than the Portland cement concretes;
2. The total free shrinkage for slag cement concrete is clearly larger than for Portland cement concrete. This difference of behaviour is mainly due to the fast and large increase in the autogenous deformation of the slag cement concrete.
Following these experimental results, the effect of the autogenous deformation on the cracking sensibility of slag cement concretes seemed interesting to investigate. Their deformations (autogenous deformation, compressive and tensile basic creep) have been studied at early age for three concretes characterized by different slag contents (0, 42 and 71%) under free and restrained conditions. For monitoring free and restrained autogenous deformations, several test rigs aimed at limiting artefacts were designed, like the TSTM (Temperature Stress Testing Machine). Moreover, the behaviour of these concretes was also characterized by a study at a macro- and microstructure scale.
Finally, this study shows that the slag cement concretes under sealed and fully restrained conditions crack later than the Portland cement concrete, despite the fact that they are characterized by the largest autogenous deformation. This behaviour is due to:
- the slag effect on the hydration reaction of cementitious material;
- the cement matrix expansion of the slag cement concretes at early age which delays the occurrence of tensile stresses inside the material;
- the largest capacity of this concrete to relax tensile stresses.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Morand, Alexandra. "Formation et instabilité de réservoirs de magma silicique dans la croûte continentale." Thesis, Université de Paris (2019-....), 2019. https://theses.md.univ-paris-diderot.fr/MORAND_Alexandra_va2.pdf.
Full textHuge silicic magmatic systems can produce devastating eruptions with emitted volumes above 100 km³. The shape and the organisation of magmatic storage are still debated, despite their crucial influence on the results of theoretical predictions. We choose to look at the problem in a new light, by thinking about the physical reasons that explain the formation of a storage zone. This is in order to better understand stresses produced by the magma chamber in the host rocks. Our hypothesis is that silicic magma, due to its positive buoyancy, rises through the ductile continental crust as a diapir, and is then stopped by the brittle-ductile transition. This PhD follows three axes. The first presents the adaptation of a published theoretical plate-model which enables us to describe the stresses and displacements due to the storage of a buoyant liquid under an elastic plate. The second axis is an experimental one. An apparatus was built to reproduce experimentally the storage configuration assumed. Our results, allow us to test our model. Thirdly, in order to validate our starting hypothesis, numerical results are compared with data from natural systems. We show that our model can reproduce the large observed deformation at Uturuncu volcano in Bolivia. Then, more broadly, we show that stresses produced in the plate by the magma chamber can produce circular faults above the storage zone. This result has direct implications for the understanding of caldera formation during large silicic eruptions
Соболев, Д. О., and D. O. Sobolev. "Неравномерность деформации в процессах правки растяжением листового проката из алюминиевых сплавов : магистерская диссертация." Master's thesis, б. и, 2020. http://hdl.handle.net/10995/94162.
Full textThe paper presents the main properties and types of flat semi-finished products made of aluminum and aluminum alloys. The technology of production of flat semi-finished products, technology and equipment for straightening by stretching are considered. New patent developments in the field of rolling flat semi-finished products from aluminum alloys are presented. The paper presents the results of a study of the non-uniformity of deformation in the process of tensile straightening of sheet metal made of aluminum alloys. The solution of the problem of tensile straightening of strips of aluminum alloys by the finite element method in the ABAQUS software package is presented in order to determine the level of deformations. The analysis of the strain distribution during tensile straightening of hot-rolled strips of aluminum alloys is carried out. Unequal values of deformations along coordinate directions are explained from the standpoint of anisotropy of properties of rolled strips.
Tawana, Siyd S. "Behavior of plain and steel fiber reinforced concrete under multiaxial stress." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1178903105.
Full textAvachat, Siddharth. "Experimental and numerical analyses of dynamic deformation and failure in marine structures subjected to underwater impulsive loads." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44904.
Full textCheng, Wentao. "In-plane shrinkage strains and their effects on welding distortion in thin-wall structures." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1124049585.
Full textTitle from first page of PDF file. Document formatted into pages; contains xx, 268 p.; also includes graphics (some col.). Includes bibliographical references (p. 256-268). Available online via OhioLINK's ETD Center
Bicalho, Julio Roberto Santos. "Modelagem computacional de um reator anaeróbico fabricado em polietileno de alta densidade rotomoldado." Universidade do Estado do Rio de Janeiro, 2007. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=415.
Full textThe present work was developed to evaluate the potential of uses of an anaerobic reactor manufactured in HDPE High Density Polyethylene produced by the rotomolding process in substitution to the conventional reactors built in stonemasonry, working in a batch regime and buried in the soil. The state of tensions and the deformations were assessed using the program of Finite Elements ABAQUS version 6.5 and the mesh of the knots using the program MSC PATRAN 2005 forming 7329 knots and 2004 elements, in an optimized mesh for the areas of larger curvature (tension concentrator points). The loading is formed with an internal pressure of the biogas of 5kPa added of biomass hydrostatic load of 6000 kg in an elastic foundation calculated by the ratio pressure/settling starting from the Module of equivalent Elasticity of the soil (Esolo). Comparing the state of tensions assessed during the loading was possible to verify that the largest tension obtained in the most critical element goes the most probable utilization of the reactor, reached the value of 7, 46 MPa (it doesn't surpass 40% of the smallest resistance value to the traction and to the shearing strain of HDPE of 20 MPa) and the largest ratio of dR/R deformation was of 1.0%. The most critical assessed case was when the reactor is buried in soil with Esolo = 1,55 MPa and material with EPEAD = 1550 MPa, totally empty and with a superficial overload in the land of 20kN/m2 generating a tension of 17,80 MPa in the element 1955 (reaching 89% of the smallest resistance value to the traction and the shearing strain of a 20 MPa HDPE). The obtained results confirmed that the reactor produced in HDPE substitutes with advantages the models manufactured in stonemasonry, supporting the internal biogas pressure and the biomass load.
Tondreau, Gilles. "Damage localization in civil engineering structures using dynamic strain measurements." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209466.
Full textmonitoring of civil engineering structures in order to locate small damages automatically. A
review of the very wide literature on Structural Health Monitoring (SHM) points first out that
the methods can be grouped in four categories based on their need or not of a numerical model,
as well as their need or not of information of the damaged structure to be applied. This state
of the art of the SHM methods highlights the requirement to reach each levels of SHM, which
is in particular for the localization of small damages in civil engineering structures the needs
for a non-model based output-only damage sensitive feature extraction technique. The origin of
the local sensitivity of strains to damages is also analyzed, which justifies their use for damage
localization.
A new method based on the modal filtering technique which consists in combining linearly
the sensor responses in a specific way to mimic a single degree of freedom system and which
was previously developed for damage detection is proposed. A very large network of dynamic
strain sensors is deployed on the structure and split into several independent local sensor networks.
Low computational cost and fast signal processing techniques are coupled to statistical
control charts for robust and fully automated damage localization.
The efficiency of the method is demonstrated using time-domain simulated data on a simply
supported beam and a three-dimensional bridge structure. The method is able to detect and
locate very small damages even in the presence of noise on the measurements and variability
of the baseline structure if strain sensors are used. The difficulty to locate damages from acceleration
sensors is also clearly illustrated. The most common classical methods for damage
localization are applied on the simply supported beam and the results show that the modal filtering
technique presents much better performances for an accurate localization of small damages
and is easier to automate.
An improvement of the modal filters method referred to as adaptive modal filters is next
proposed in order to enhance the ability to localize small damages, as well as to follow their
evolution through modal filters updating. Based on this study, a new damage sensitive feature
is proposed and is compared with other damage sensitive features to detect the damages with
modal filters to demonstrate its interest. These expectations are verified numerically with the
three-dimensional bridge structure, and the results show that the adaptation of the modal filters
increases the sensitivity of local filters to damages.
Experimental tests have been led first to check the feasibility of modal filters to detect damages
when they are used with accelerometers. Two case studies are considered. The first work
investigates the experimental damage detection of a small aircraft wing equipped with a network
of 15 accelerometers, one force transducer and excited with an electro-dynamic shaker. A
damage is introduced by replacing inspection panels with damaged panels. A modified version
of the modal filtering technique is applied and compared with the damage detection based principal
component analysis of FRFs as well as of transmissibilities. The three approaches succeed
in the damage detection but we illustrate the advantage of using the modal filtering algorithm as
well as of the new damage sensitive feature. The second experimental application aims at detecting
both linear and nonlinear damage scenarios using the responses of four accelerometers
installed on the three-storey frame structure previously developed and studied at Los Alamos
National Labs. In particular, modal filters are shown to be sensitive to both types of damages,
but cannot make the distinction between linear and nonlinear damages.
Finally, the new method is tested experimentally to locate damages by considering cheap
piezoelectric patches (PVDF) for dynamic strain measurements. Again, two case studies are investigated.
The first work investigates a small clamped-free steel plate equipped with 8 PVDFs sensors, and excited with a PZT patch. A small damage is introduced at different locations by
fixing a stiffener. The modal filters are applied on three local filters in order to locate damage.
Univariate control charts allow to locate automatically all the damage positions correctly.
The last experimental investigation is devoted to a 3.78m long I-steel beam equipped with 20
PVDFs sensors and excited with an electro-dynamic shaker. Again, a small stiffener is added to
mimic the effect of a small damage and five local filters are defined to locate the damage. The
damage is correctly located for several positions, and the interest of including measurements
under different environmental conditions for the baseline as well as overlapping the local filters
is illustrated.
The very nice results obtained with these first experimental applications of modal filters
based on strains show the real interest of this very low computational cost method for outputonly
non-model based automated damage localization of real structures.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
Petrlíková, Helena. "Pevnostní analýza řezných nástrojů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2010. http://www.nusl.cz/ntk/nusl-229336.
Full textAlaluss, Khaled Ahmed. "Modellbildung und Simulation des Plasma-Schweißens zur Entwicklung innovativer Schweißbrenner." Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-216002.
Full textIn this work, technical and constructive solutions were developed based on simulation models (process and structural) for fluid mechanical, thermomechanical and magneto-hydrodynamic effects. The simulation process included improving and characterising the physical operating principles for micro plasma welding, high performance plasma welding and orbital plasma welding. Also, the physical effects for the above plasma welding processes were studied and analysed. From these different physical properties of the parameters for the plasma welding processes, and their effects on plasma welding process behaviour and torch design were analysed and characterised. The results were used for the development and construction of plasma welding torch models, which included material selection and geometrical design such as, process gas supply design, torch cooling system design, and other related torch designs. By developing the thermomechanical simulation model, deformations and residual stresses that were generated by heating during the plasma welding process were investigated and analysed. The developed thermomechanical model included material, structural and welding specifications such as buffering and preheating. Simulations utilizing this model were used in order to reduce the residual stresses and deformations of the welded components
Alaluss, Khaled Ahmed. "Modellbildung und Simulation des Plasma-Schweißens zur Entwicklung innovativer Schweißbrenner." Universitätsverlag Chemnitz, 2015. https://monarch.qucosa.de/id/qucosa%3A20614.
Full textIn this work, technical and constructive solutions were developed based on simulation models (process and structural) for fluid mechanical, thermomechanical and magneto-hydrodynamic effects. The simulation process included improving and characterising the physical operating principles for micro plasma welding, high performance plasma welding and orbital plasma welding. Also, the physical effects for the above plasma welding processes were studied and analysed. From these different physical properties of the parameters for the plasma welding processes, and their effects on plasma welding process behaviour and torch design were analysed and characterised. The results were used for the development and construction of plasma welding torch models, which included material selection and geometrical design such as, process gas supply design, torch cooling system design, and other related torch designs. By developing the thermomechanical simulation model, deformations and residual stresses that were generated by heating during the plasma welding process were investigated and analysed. The developed thermomechanical model included material, structural and welding specifications such as buffering and preheating. Simulations utilizing this model were used in order to reduce the residual stresses and deformations of the welded components.
Karavelić, Emir. "Stochastic Galerkin finite element method in application to identification problems for failure models parameters in heterogeneous materials." Thesis, Compiègne, 2019. http://www.theses.fr/2019COMP2501.
Full textThis thesis deals with the localized failure for structures built of heterogeneous composite material, such as concrete, at two different scale. These two scale are latter connected through the stochastic upscaling, where any information obtained at meso-scale are used as prior knowledge at macro-scale. At meso scale, lattice model is used to represent the multi-phase structure of concrete, namely cement and aggregates. The beam element represented by 3D Timoshenko beam embedded with strong discontinuities ensures complete mesh independency of crack propagation. Geometry of aggregate size is taken in agreement with EMPA and Fuller curve while Poisson distribution is used for spatial distribution. Material properties of each phase is obtained with Gaussian distribution which takes into account the Interface Transition Zone (ITZ) through the weakening of concrete. At macro scale multisurface plasticity model is chosen that takes into account both the contribution of a strain hardening with non-associative flow rule as well as a strain softening model components for full set of different 3D failure modes. The plasticity model is represented with Drucker-Prager yield criterion, with similar plastic potential function governing hardening behavior while strain softening behavior is represented with St. Venant criterion. The identification procedure for macro-scale model is perfomed in sequential way. Due to the fact that all ingredients of macro-scale model have physical interpretation we made calibration of material parameters relevant to particular stage. This approach is latter used for model reduction from meso-scale model to macro-scale model where all scales are considered as uncertain and probability computation is performed. When we are modeling homogeneous material each unknown parameter of reduced model is modeled as a random variable while for heterogeneous material, these material parameters are described as random fields. In order to make appropriate discretizations we choose p-method mesh refinement over probability domain and h-method over spatial domain. The forward model outputs are constructed by using Stochastic Galerkin method providing outputs more quickly the the full forward model. The probabilistic procedure of identification is performed with two different methods based on Bayes’s theorem that allows incorporating new observation generated in a particular loading program. The first method Markov Chain Monte Carlo (MCMC) is identified as updating the measure, whereas the second method Polynomial Chaos Kalman Filter (PceKF) is updating the measurable function. The implementation aspects of presented models are given in full detail as well as their validation throughthe numerical examples against the experimental results or against the benchmarks available from literature
Мариношенко, Олександр Петрович. "Динамічне деформування видовжених балкових систем набігаючим повітряним потоком." Doctoral thesis, 2010. https://ela.kpi.ua/handle/123456789/694.
Full textHuang-Chao-Hsiang and 黃昭翔. "Moisture-Induced Deformations and Stresses in Plastic IC Packages." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/63655368776646599917.
Full text長庚大學
機械工程研究所
89
The characteristics of moisture absorption and desorption of plastic molding compound has been a serious factor of influencing the deformations and stresses, as well as reliability of electronic packages. In case of moisture entering the package component during the thermo-mechanical tests, it would results in extra deformations and stresses to the experimental data and thus leaded into the significant error of the experimental determination. The hygroscopic-induced deformations of epoxy molding compound (EMC) and two-layer packages of quad flat non-lead (QFN) without a chip inside are investigated experimentally and numerically in this study. The experimental measurements have been done by two full-field laser interferometric methods; real-time moiré interferometry and real-time Twymen-Green interferometry systems. Moiré interferometry can provide an in-plane displacement measurement, while Twymen-Green interferometry is used for measuring the out-of-plane displacements. For numerical analyses, the finite element method was adopted for validating the ex-perimental observations and further understanding the hydrothermal mechanics of QFN. In the hygroscopic problem of EMC materials, the tendency of moisture absorp-tion and desorption of EMC on heating and preservation conditions have been char-acterized through experiments. It is also shown that moisture change and moisture-induced strains appeared a linear relationship in which the slope called as the coeffi-cient of moisture expansion, was determined. The hygrothermo-mechanical behaviors of non-chip QFN were investigated experimentally and numerically. The full-field in-plane deformations on the cross-section through thickness and out-of plane deforma-tions on the top of the surface, caused by moisture and temperature individually and combinationally, were determined. The experimental results have been validated by the finite element and theoretical analyses. The present study has laid down the fun-damental mechanics and approaches for the non-chip QFN packaging structural des-ign and analysis in terms of hygrothermal effects.
黃紹庚. "Thermal Induced Deformations and Stresses of Stacked Die Packages." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/8yby52.
Full text長庚大學
機械工程研究所
92
ABSTRACT The objectives of this research are to apply definite element methods in the analysis of thermal induced deformations and stresses of stacked die packages, and then in combination of multi-layer assembly theory and instant measuring Twyman-Green interference system, to verify the effectiveness of a definite element analysis model. First, thermal deformation and stress caused by the stacked die packages on the process have been studied and explored in serial. Second, deal with die attach of the stacked die packages, and single-lap joint tensile testing is applied to measure the adhesive strength of die attach. Finally, calculate the actual stress distribution of die attach and give further exploration. In the analysis of mechanics, the consistency of definite element analysis and theory analysis proves that there shows insignificant influences on overall stress distribution on the models with or without beveling, rendering great help to simplified 3D model. From further analysis, we have learned that on the stacked die packages process, the maximum peel stress and share stress occur on the symmetrical end of the top layer die attach, which helps understand mechanics behavior on the die attach process or under thermal loads. In the issue of thermal deformation, instant Twyman-Green measuring system is used to measure warping status of stacked die package heated from room temperature to 120oC and the temperature of specimen is found on the increase, and through glass of die attach, temperature is converted to 100 oC, and then lower it to room temperature, and the warpage resumes to as it was. This experiment proves that die attach has insignificant influence on overall packages and the experimental results show that the deformation and warping of stacked die packages would be diverse in geometric shape of internal stacked die. A further exploration goes to the single-lap joint tensile testing with die attach and in consideration of influence on adhesive strength in high-temperature and high humidity. The findings reveal that the average shear stress is 26Mpa below the room temperature, and at high-temperature and high-humidity, the average shear stress is 11Mpa. In the light of theory and FEM analysis, we learn that the share stress of die attach is actually three times greater than average shear stress. Judging from the stress distributions of single-lap joint, we need to put shear stress and peel stress into consideration before we can find out the actual adhesive strength.
Tung, Wang Chih, and 王志棟. "EMC-Induced Thermal Deformations and Residual Stresses in IC Packaging." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/76072561309300281131.
Full text長庚大學
機械工程研究所
90
EMC-induced thermal deformations and residual stresses in IC packaging are investigated experimentally, theoretically and numerically. A real-time Twyman-Green interferometry is used for measuring the out-of-plane deformations, while dynamic mechanical analysis (DMA) and thermo mechanical analysis (TMA) are for characterizing mechanical properties of epoxy mold compound (EMC). Experimental observations associated with numerical simulation and theoretical predictions are used for understanding the thermal deformations and residual stresses of IC packages due to EMC. The mechanical properties of EMC materials, including elastic modulus (E), glass transition temperature (Tg) and coefficient of thermal expansion (CTE) have been characterized by DMA and TMA experiments. It is shown that EMC materials must be fully cured so that the material properties can be stable for applications. The real-time Twyman-Green interferometry has provided the deformations of die/EMC bi-material structure after the molding process prior to post mold curing (PMC). It is shown that residual deformations are not equal at the in-plane (x-y) direction. The volume shrinkage of EMC would induce the stresses during the high temperature molding process, but its viscoelasticity effect relaxed these stresses during the PMC process. The experimental results have demonstrated that die/EMC bi-material structure reverse warp at high temperature and viscoelasticity effect of EMC relaxed some stresses after many times or a long period of time of solder reflow process. Due to the zero-stress shifting to the high temperature, the residual deformations of die/EMC bi-material structure increased 40 ﹪after cooling down to the room temperature. For mechanics verification by comparing with experimental, theoretical, and FEM results, the mechanics behaviors of die/EMC bi-material structure under thermal loads have been resolved during the manufacturing process. Because of the free edge effects due to material and geometry discontinuous, interlaminar shear stresses and peel stresses start to occur at the structural interface and near the free boundary. The uniform distributions of axial stress exist at the region ranging from x=0-0.75L at low temperature down to x=0-0.4L at high temperature. The max. warpage and axial stressess caused by unit temperature change were found at 155℃ to 165℃. Although these can be changed due to viscoelastic stress relaxation, but these should be taken into account especially under thermal shock loading