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Li, You-Sheng. "Heat capacity measurements of Sr₂RuO₄ under uniaxial stress". Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16591.
Pełny tekst źródłaBarber, Mark E. "Uniaxial stress technique and investigations into correlated electron systems". Thesis, University of St Andrews, 2017. http://hdl.handle.net/10023/15429.
Pełny tekst źródłaCampbell, Brendan Anthony. "Annealing, uniaxial stress and isotope effects in radiation damaged diamond". Thesis, King's College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408149.
Pełny tekst źródłaHartnett, S. J. "Uniaxial stress/DLTS studies on deep level defects in n-GaAs". Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.361362.
Pełny tekst źródłaMitra, Abhijit. "LABORATORY INVESTIGATION OF COAL PERMEABILITY UNDER REPLICATED IN SITU STRESS REGIME". OpenSIUC, 2010. https://opensiuc.lib.siu.edu/dissertations/124.
Pełny tekst źródłaRau, Georg. "Theory of the electronic and optical properties of GaAs/AlGaAs quantum wells under uniaxial stress". Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.298423.
Pełny tekst źródłaThapa, Romit. "Uniaxial and Biaxial Restraint in Concrete Pavement Undergoing Alkali-Silica Reaction". Youngstown State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1533123602865294.
Pełny tekst źródłaChen, Wen. "Uniaxial behaviour of suction caissons in soft deposits in deepwater". University of Western Australia. School of Civil and Resource Engineering, 2005. http://theses.library.uwa.edu.au/adt-WU2005.0136.
Pełny tekst źródłaSviridov, Viacheslav [Verfasser]. "Stress-Dependent Elastic Properties of Anisotropic Sedimentary Rocks: Uniaxial and Triaxial Experiments and Theoretical Modelling / Viacheslav Sviridov". Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1176638718/34.
Pełny tekst źródłaCoates, Terrence Joseph. "Effects of uniaxial tensile stress on magnetic flux leakage and magnetic Barkhausen noise around blind-hole pits in steel". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0002/MQ42600.pdf.
Pełny tekst źródłaHartig, Jens. "Numerical investigations on the uniaxial tensile behaviour of Textile Reinforced Concrete". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2011. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-66614.
Pełny tekst źródłaDie vorliegende Arbeit beschäftigt sich mit Untersuchungen zum einaxialen Zugtragverhalten von Textilbeton. Textilbeton ist ein Verbundwerkstoff bestehend aus einer Matrix aus Feinbeton und einer Bewehrung aus Multifilamentgarnen aus Hochleistungsfasern, welche zu textilen Strukturen verarbeitet sind. Die Untersuchungen konzentrieren sich auf Bewehrungen aus alkali-resistentem Glas. Das Tragverhalten des Verbundwerkstoffs ist komplex, was aus der Heterogenität der Matrix und der Garne sowie der unvollständigen Durchdringung der Garne mit Matrix resultiert. Das Hauptziel der Arbeit ist die theoretische Untersuchung von Effekten und Mechanismen innerhalb des Lastabtragverhaltens von Textilbeton, welche nicht vollständig anhand verfügbarer experimenteller Ergebnisse erklärt werden können. Das entsprechende Modell zur Beschreibung des Zugtragverhaltens von Textilbeton soll verschiedene experimentelle Versuchstypen mit einem einheitlichen Modell abbilden können. Unter Vernachlässigung von Querdehneffekten wurde ein eindimensionales Modell entwickelt und im Rahmen der Finite-Elemente-Methode numerisch implementiert. Es werden jedoch auch Lastabtragmechanismen in Querrichtung durch eine Unterteilung der Bewehrungsgarne in sogenannte Segmente berücksichtigt. Das Modell enthält zwei Typen von finiten Elementen: Stabelemente und Verbundelemente. In Längsrichtung werden Stabelemente kettenförmig angeordnet, um das Tragverhalten von Matrix und Bewehrung abzubilden. In Querrichtung sind die Stabelementketten mit Verbundelementen gekoppelt. Das Modell erhält seine Komplexität hauptsächlich aus Nichtlinearitäten in der Materialbeschreibung, z.B. durch begrenzte Zugfestigkeiten von Matrix und Bewehrung, Zugentfestigung der Matrix, Welligkeit der Bewehrung und nichtlineare Verbundgesetze. Neben einer deterministischen Beschreibung des Materialverhaltens beinhaltet das Modell auch eine stochastische Beschreibung auf Grundlage eines Zufallsfeldansatzes. Mit dem Modell können Spannungsverteilungen im Verbundwerkstoff und Eigenschaften der Betonrissentwicklung, z.B. in Form von Rissbreiten und Rissabständen untersucht werden, was in dieser Kombination nur mit wenigen der existierenden Modelle für Textilbeton möglich ist. In vielen der vorhandenen Modelle sind diese Eigenschaften Eingangsgrößen für die Berechnungen und keine Ergebnisse. Darüber hinaus kann anhand des Modells auch das sukzessive Versagen der Bewehrungsgarne studiert werden. Das Modell wurde auf drei verschiedene Versuchstypen angewendet: den Filamentauszugversuch, den Garnauszugversuch und Dehnkörperversuche. Die Berechnungsergebnisse zu den Filamentauszugversuchen zeigten eine gute Übereinstimmung mit experimentellen Resultaten. Zudem wurden Parameterstudien durchgeführt, um Einflüsse aus Geometrieeigenschaften wie der eingebetteten und freien Filamentlänge sowie Materialeigenschaften wie dem Verbund zwischen Matrix und Filament zu untersuchen. Die Berechnungsergebnisse zum Garnauszugversuch demonstrierten die Anwendbarkeit des Modells auf diesen Versuchstyp. Es wurde gezeigt, dass für eine realitätsnahe Abbildung des Versagensverhaltens der Bewehrungsgarne eine relativ feine Auflösung der Bewehrung notwendig ist. Die Berechnungen lieferten die Verteilung von Versagenspositionen in der Bewehrung und die Entwicklung der Degradation der Garne im Belastungsverlauf. Ein Hauptziel der Arbeit war die Untersuchung von Effekten im Zugtragverhalten von Textilbeton, die bisher nicht durch experimentelle Untersuchungen erklärt werden konnten. Daher wurde eine Vielzahl von Parameterstudien zu Dehnkörpern mit mehrfacher Matrixrissbildung, welche das Zugtragverhalten von Textilbeton ähnlich praktischen Anwendungen abbilden, durchgeführt. Die Berechnungsergebnisse zeigten, dass der experimentell beobachtete dreigeteilte Verlauf der Spannungs-Dehnungs-Beziehung von Textilbeton bestehend aus dem ungerissenen Zustand, dem Zustand der Matrixrissbildung und dem Zustand der abgeschlossenen Rissbildung vom Modell wiedergegeben wird. Die beste Übereinstimmung zwischen berechneten und experimentellen Ergebnissen ergab sich unter Einbeziehung von Streuungen in den Materialeigenschaften der Matrix, der Zugentfestigung der Matrix und der Welligkeit der Bewehrung
Zhang, Xuesong, i n/a. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion". Griffith University. School of Engineering, 2003. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20051104.153239.
Pełny tekst źródłaZhang, Xuesong. "Punching Shear Failure Analysis of Reinforced Concrete Flat Plates Using Simplified Ust Failure Criterion". Thesis, Griffith University, 2003. http://hdl.handle.net/10072/365777.
Pełny tekst źródłaThesis (Masters)
Master of Philosophy (MPhil)
School of Engineering
Full Text
Souza, Márcio Alves Sodré de. "Efeito da tensão mecânica no ruído de baixa frequência de transistores SOI planares e tridimensionais". Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-15072016-142254/.
Pełny tekst źródłaThis work presents a study of the uniaxial and biaxial mechanical stress effect on low frequency noise in planar and three-dimensional SOI transistors (triple gate) with different crystal orientation, and an study of analog parameters in planar and for triple gate MuGFET. In planar transistor, the study of low frequency noise showed an improvement in low frequency noise for strained transistors in saturation regime, regardless of the channel length, however for the linear regime, the mechanical stress only reduced the noise in a small channel length (160nm). In the analog characteristics was used the feature of two-dimensional numerical simulation for the expansion of the results. The results shows that the strained transistors are capable to promoting a better performance in transconductance in a order at least 40%, indicating for a long channel lengths (910nm) an improvement of 56% in favor of biaxial stress and the opposite to uniaxial (45%) (160nm), however in the output conductance, the mechanical stress promotes higher degradation, ranging from 3% to uniaxial transistor and 105% for biaxial transistor. The intrinsic voltage gain, the strained transistors improved the performance, but in this case a best result was found for the biaxial strain reaching 5 dB. In triple gate transistors, the analysis of noise was performed on strained and conventional operating in saturation, and generally the worsening of mechanical stress on the low frequency noise in a order of magnitude for the marrow transistor, occurring only barely perceptible improvement seen in wider transistor or quasi-planar. The noise analysis for rotated transistors in linear region, showed a 1/f noise characteristic governed by the carrier number of fluctuations associated with fluctuations in mobility, the mechanical stress worsens the noise, however, by adding the substrate rotation occurs improves noise due to reduction of interface traps leading to a better sidewall interface. For larger devices the top plane suffer an increase of interface traps, worsening the top interface due to rotation of the substrate, causing a worse noise. In the analog characteristics, the triple gate MuGFETs transistors with mechanical stress and rotated substrate were studied, where the rotation of the substrate in 45º plus mechanical stress promoted a worsening of the results, particularly in the transconductance, where the worsening ranged from 45% up to 15% for a narrow device (20 nm) and a large (870 nm).
Sharma, Henu. "Theoretical studies of PbTiO3 and SrTiO3 under uniaxial mechanical constraints combining firstprinciples calculations and phenomenological Landau theory". Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENI078.
Pełny tekst źródłaIn the present thesis we present theoretical studies of perovskite compounds under uniax-ial mechanical constraints combining first-principles DFT calculations approach and phe-nomenological Landau theory. ABO3 perovskites form a very important class of functionalmaterials that can exhibit a broad range of properties (e.g., superconductivity, magnetism,ferroelectricity, multiferroism, metal-insulator transitions. . . ) within small distortions ofthe same simple prototype cubic structure. Though these compounds have been exten-sively studied both experimentally and computationally, there are still unresolved issuesregarding the effect of pressure. In recent years, strain engineering has reported to bean original approach to tune the ferroelectric properties of perovskite ABO3 compounds.While the effect of epitaxial biaxial strain and hydrostatic strain is rather well understoodin this class of materials, very little is yet known regarding the effect of uniaxial mechanicalconstraints. Our study is motivated by the little existing understanding of the effect ofuniaxial strain and stress, that has been up to now almost totally neglected. Two proto-type compounds are studied in detail: PbTiO3 and SrTiO3. After a general introductionon ABO3 compounds and calculations techniques (ab initio and phenomenological Landaumodel), we studied the effect of mechanical constraints in these compounds in our thesis.PbTiO3 is a prototypical ferroelectric compound and also one of the parent components ofthe Pb(Zr,Ti)O3 solid solution (PZT), which is the most widely used piezoelectrics. ForPbTiO3, we have shown that irrespectively of the uniaxial mechanical constraint applied,the system keeps a purely ferroelectric ground-state, with the polarization aligned eitheralong the constraint direction (FEz phase) or along one of the pseudocubic axis perpen-dicular to it (FEx phase). This contrasts with the case of isotropic or biaxial mechanicalconstraints for which novel phases combining ferroelectric and antiferrodistortive motionshave been previously reported. Under uniaxial strain, PbTiO3 switches from a FEx groundstate under compressive strain to FEz ground-state under tensile strain, beyond a critical strain !czz! +1%. Under uniaxial stress, PbTiO3 exhibits either a FEx ground state undercompression ("zz < 0) or a FEz ground state under tension ("zz > 0). Here, however, anabrupt jump of the structural parameters is also predicted under both compressive andtensile stresses at critical values "zz! +2 GPa and −8 GPa. This behavior appears similarto that predicted under negative isotropic pressure and might reveal practically useful toenhance the piezoelectric response in nanodevices.The second compound of interest is SrTiO3. It has been widely studied in the past decadesdue to its unusual properties at low temperature. In this work, we have extended ourprevious investigations on PbTiO3 by exploring theoretically the pressure effects on per-ovskite SrTiO3 combining the first-principles calculations and a phenomenological Landaumodel. We have discussed the evolution of phonon frequencies of SrTiO3 with the threeisotropic, uniaxial and biaxial strains using first-principles calculations. We also reproducethe previous work done in SrTiO3 with epitaxial strain and hydrostatic strain. Finally,we have calculated the phase diagram of SrTiO3 under uniaxial strain, as obtained fromLandau theory and discussed how it compares with the first-principles calculations
Gonzales, Manny. "The mechanochemistry in heterogeneous reactive powder mixtures under high-strain-rate loading and shock compression". Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54393.
Pełny tekst źródłaDuffrene, Lucas. "Comportement viscoélastique d'un verre silico-sodocalcique dans le domaine des températures intermédiaires : approche phénoménologique et modélisation en triaxialité". Paris, ENMP, 1994. http://www.theses.fr/1994ENMP0515.
Pełny tekst źródłaZang, Yong Hua. "Contribution a l'etude des proprietes viscoelastiques de caoutchoucs reticules et de liquides polystyrenes". Université Louis Pasteur (Strasbourg) (1971-2008), 1987. http://www.theses.fr/1987STR13225.
Pełny tekst źródłaBarragán, Bryan Erick. "Failure and toughness of steel fiber reinforced concrete under tension and shear". Doctoral thesis, Universitat Politècnica de Catalunya, 2002. http://hdl.handle.net/10803/5905.
Pełny tekst źródłaEl comportamiento a tracción uniaxial del hormigón reforzado con fibras de acero se caracteriza utilizando cilindros entallados, elaborados con hormigones de resistencia normal y alta, con y sin fibras de acero. La metodología se extiende también para testigos extraídos de elementos de mayor tamaño. Los resultados se utilizan para definir parámetros de tenacidad y resistencia equivalentes de post-pico utilizables para representar el comportamiento del material y para un posible diseño estructural. Además, se desarrolla un estudio paramétrico experimental, que considera diferentes variables del ensayo y forma de probetas, para definir una configuración confiable del ensayo. Se analizan los modos de rotura observados y se evalúa la respuesta tensión-ancho de fisura. Asimismo, se propone una relación tensión-apertura de fisura característica para el diseño y análisis estructural. El comportamiento a tracción uniaxial se compara también con el de flexión y tracción por compresión diametral.
La fractura por cortante se estudia a nivel material, en hormigones de resistencia normal y alta, con y sin fibras de acero, utilizando la configuración de cortante directo denominada push-off. Se analizan el modo de rotura y la respuesta tensión-desplazamiento. Además, se definen parámetros basados en la tenacidad y tensiones equivalentes de cortante para una posible utilización en el diseño estructural.
Con el fin de obtener resultados que validen la utilización de las fibras de acero como refuerzo de cortante y al mismo tiempo estudiar la fractura por cortante a nivel estructural, se han realizado ensayos a escala real sobre vigas de sección rectangular y en T. Se analizan las respuestas carga-flecha y carga-ancho de fisura de vigas rectangulares de hormigón reforzado con fibras de acero variando su altura y de vigas T variando las dimensiones del ala. Los resultados obtenidos experimentalmente se utilizan para verificar la aplicabilidad de los métodos de diseño existentes en el caso del hormigón reforzado con fibras de acero. Además, se presenta una propuesta para el diseño a cortante basada en la respuesta tensión-desplazamiento relativo obtenida a partir del ensayo push-off de cortante directo.
The thesis deals with the characterization of the failure of steel fiber reinforced concrete (SFRC) in tension and shear, on the material level, and the determination of parameters that represent the toughness in these two modes of failure. Tests have been performed on large-scale beams failing under shear failure, which have been analyzed using existing design code formulas. The toughness parameters determined from the material are used in the design against such failure.
The uniaxial tensile behavior of SFRC is characterized using notched cylinders of normal and high strength concretes, with and without steel fibers. The methodology is also extended to cores extracted from large elements. Results are used to define toughness parameters and equivalent post-peak strengths to be used for representing the material behavior and for possible structural design. Furthermore, a parametric study considering different test variables and specimen shape is carried out in order to define a reliable test configuration. The observed modes of failure are analyzed and the stress-crack width response is evaluated. Also, a characteristic stress-crack width response is proposed for structural analysis and design. The uniaxial tension behavior is also compared with that of flexural and splitting-tension.
The shear failure is studied using the direct shear push-off test configuration, in normal and high strength concretes with and without steel fibers. The mode of failure and the stress-slip and stress-crack opening responses are analyzed. Toughness parameters and equivalent shear strengths based on the test results are defined for structural design.
In order to provide results for validating the use of steel fibers as shear reinforcement and for studying shear failure at the structural level, full-scale tests on rectangular and T-beams were performed. The load-deflection and load-crack width responses are analyzed and compared with results of plain concrete beam tests. The experimentally-obtained results are used to evaluate the applicability of existing design methods for steel fiber reinforced concrete. Furthermore, a proposal for shear design based on the shear stress versus slip relationship from the push-off shear test is presented.
Good, Mattias. "Structural analysis of thermal interface materials and printed circuit boards in telecom units - a methodology". Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-59746.
Pełny tekst źródłaA structural analysis on Ericssons MINILINK-6352 has been performed in order to investigate stresses and deformations of the unit, mainly focusing on the thermal interface materials and warpage of the printed circuit boards. These are important aspects when considering if the unit is thermally adequate from a mechanical point of view, where good surface contact between various bodies are critical for proper cooling through heat conductivity. The analysis requires sufficient materal data for the interface material and the circuit board in order to create suitable mathematical models. Uniaxial compression tests have been conducted to characterise the hyperelastic and viscoelastic constitutive laws of a filled silicone rubber material used as a thermal interface material, commonly referred to as a thermal pad. Bending of a printed circuit board was simulated and compared to a three-point bend test on the circuit board in order to verify material data already available in the computational software, which showed good agreement. The entire radio unit was mechanically analysed during its sealing process. The circuit board with attached components modelled as stiff blocks with thermal pads on top compressed by plates was simulated and a weak area was found. This area in question was already known and has in a later stage been eliminated by adding an additional supporting pillar. Hence this study shows a methodology to find regions of interest at an early design phase which can easily be altered to fulfil necessary requirements and eliminate design flaws. This work has proven useful in finding weak regions in the example product, it also provides enough information and example data to further investigate similar products. The combination of experience and simulation allows for smarter design choices.
Guillaume, Alexandre. "Transitions de phases dans les fermions lourds sous contrainte uniaxiale". Université Joseph Fourier (Grenoble), 1999. http://www.theses.fr/1999GRE10060.
Pełny tekst źródłaMorland, Catherine. "Etude de la contrainte et de l'orientation dans les reseaux d'elastomeres diformes". Paris 6, 1987. http://www.theses.fr/1987PA066057.
Pełny tekst źródłaBelmehdi, Yassine. "Contribution à l'identification de nouveaux indicateurs de défaillance des modules de puissance à IGBT". Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14258/document.
Pełny tekst źródłaPower electronics has a role increasingly growing up in transport:electric and hybrid vehicles, trains and aircraft. For these applications, security is a critical point, thus the reliability of the power assembly must be optimized. The knowledge of time to failure is very important information for the designers of these systems. Inthis context, an early failure indicator would predict system failuresbefore it becomes effective. In this thesis, we focused on the electromechanical characterization of power transistors: MOSFET and IGBT. Based on these results this electromechanical characterization should help us in the longer term, to highlight an early failure indicator of the power assembly
Giannotta, Jean-Claude. "Comportement mecanique et evolution structurale de cuivres de haute purete dans le domaine dynamique". Paris, ENMP, 1986. http://www.theses.fr/1986ENMP0029.
Pełny tekst źródłaAl-Nasser, Amin Eyad. "Characterization of Sheet Materials for Stamping and Finite Element Simulation of Sheet Hydroforming". The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1243953225.
Pełny tekst źródłaNoudem, Jacques Guillaume. "Texturation des céramiques supraconductrices Bi-Pb-Sr-Ca-Cu-O par combinaison des effets du champ magnétique et de la contrainte uniaxiale à haute température". Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10169.
Pełny tekst źródłaRenversade, Loïc. "Analyse expérimentale et numérique de la plasticité à l’échelle des grains individuels dans un polycristal d’aluminium déformé en traction uniaxiale". Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEM019/document.
Pełny tekst źródłaThis work aims to improve our understanding of the local deformation of polycrystalline materials. To this end, in situ synchrotron experiments and finite element simulations are coupled to study the individual grain responses in an aluminium polycrystal during plastic deformation.In the experiment, the initial microstructure is mapped by Diffraction Contrast Tomography (DCT). The specimen is deformed in uniaxial tension and 466 grains are followed by 3D X-Ray Diffraction (3DXRD) up to 4.5% plastic strain. New original analysis methods provide the grain average orientations, elastic strains and stresses, and allow determining the intra-grain orientation distributions from the 3DXRD measurements.In the simulation, the real microstructure (DCT) is modeled by a Laguerre tessellation, finely meshed and submitted to the experimental loading. The resulting mechanical and orientation fields can be compared to the experimental data.The comparison reveals a first-order agreement between experiment and simulation. The experimental rotations exhibit a high variability, associated to grain interaction and well reproduced in the simulation. The orientation distributions exhibit preferential spread directions perpendicular to the tensile direction, which can be related to the deformation mechanisms. Lastly, the stresses are found to be in agreement within the measurement accuracies. Such a rich dataset provides routes to improve crystal plasticity models
Král, Petr. "Verifikace nelineárních materiálových modelů betonu". Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227601.
Pełny tekst źródłaJakel, Roland. "Grundlagen der Elasto-Plastizität in Creo Simulate - Theorie und Anwendung". Universitätsbibliothek Chemnitz, 2012. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-87141.
Pełny tekst źródłaThis presentation describes the basics of elasto-plasticity and its application with the finite element software Creo Simulate (formerly Pro/MECHANICA) from PTC. The first part describes the characteristics of plastic behavior, different plastic material laws, yield criteria for multiaxial stress states and different hardening models. In the second part, the opportunities and limitations of analyzing elasto-plastic problems with the FEM-code are described and user information is provided. The last part finally presents different examples. Deeply treated is the behavior of a uniaxial tensile test specimen before and after elongation with necking appears
Baumgarten, Lars. "Gesteinsmechanische Versuche und petrophysikalische Untersuchungen – Laborergebnisse und numerische Simulationen". Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2016. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-202612.
Pełny tekst źródłaYi-Wei, Chang. "Uniaxial Stress-Strain Behavior of MWCNT-Reinforced Epoxy-Matrix Composites". 2005. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0009-0112200611361168.
Pełny tekst źródłaChang, Yi-Wei, i 張益瑋. "Uniaxial Stress-Strain Behavior of MWCNT-Reinforced Epoxy-Matrix Composites". Thesis, 2005. http://ndltd.ncl.edu.tw/handle/28358134028948908663.
Pełny tekst źródła元智大學
機械工程學系
94
Due to its excellent stiffness and strength, the carbon nanotube (CNT) is considered as an ideal candidate for reinforcement in composites. In the present work, the epoxy resin is used as the matrix whereas multi-walled carbon nanotubes (MWCNTs) with various diameters are used as the reinforcement. The composite is subjected to uniaxial tension and the effects of CNT weight fraction and CNT diameter on the mechanical properties of the composite are studied. The experiment results show that the Young modulus of 5 wt% CNT/epoxy composites with a CNT diameter D < 20 nm and D = 40 ~ 60 nm is 4.56 GPa and 4.36 GPa, and the tensile strength is 52.89 MPa and 46.80 MPa, respectively, whereas the Young modulus and the tensile strength of the pure epoxy is 2.83 GPa and 25.67 MPa, respectively. Micromechanics models are developed to predict the Young modulus of CNT-reinforced composites. The predicted Young moduli are benchmarked with the experimental data of MWCNT-reinforced epoxy-matrix composites.
Lin, You-Lun, i 林佑倫. "A Three-Dimensional Equivalent Uniaxial Strain and Stress Constitutive Model". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/85x5ek.
Pełny tekst źródła國立中央大學
土木工程學系
105
This research presents a three-dimensional constitutive model of material based on the concept of equivalent uniaxial strain in order to decouple Poisson’s effect in multiaxial loading condition. The equivalent uniaxial strain is a fictitious material index which is invented to compute the parameters such as material stiffness modulus and Poisson’s ratio. The characteristics of uniaxial stress-strain model which defined by the ultimate strength parameters are obtain from material failure surface and the ultimate strength parameters varies with current stress or strain state. This research contains not only concrete material but also rock material and metal material, exerted by monotonic loading, proportional loading non-proportional loading and cyclic loading. A hypothesis of kinematic cap model is proposed to reflect the influence of the non-proportional loading path. Further, a hypothesis of softening model is applied on concrete and rock material not only to simulate post-peak branch behavior but to reflect the transition between brittle softening and ductile softening under different confining pressure. In concrete material established closed Menetrey-Willam (CMW) failure model which combined with Menetrey-Willam meridian and the cap model in concrete material and replaced Menetrey-Willam meridian with Drucker-Prager criterion in rock material. Saenz stress-strain model is applied and adjusted by the ultimate strength parameters from material failure model to reflect the latest stress or strain condition in both concrete and rock material. von-Mises criterion is applied to build material failure model for metal material as well. Correlation studies with available experimental tests are presented to valid the performance of proposed three d constitutive of materials.
Yen, Yu-Cheng, i 顏昱丞. "Equivalent Uniaxial Strain And Stress Material Constitutive Model Under Dynamic Loading". Thesis, 2018. http://ndltd.ncl.edu.tw/handle/jyt44t.
Pełny tekst źródła國立中央大學
土木工程學系
107
This research presents a dynamic three-dimensional constitutive model of material equivalent uniaxial strain and stress. The purpose is to study the behavior of concrete materials under dynamic loading, because most of the structures in daily life are subject to dynamic loading such as earthquakes, impacts and explosions. This research uses the equivalent uniaxial strain concept proposed by Darwin & Pecknold to separate the Poisson's ratio of multi-axial forces. The equivalent uniaxial strain is a fictitious material index which is invented to compute the parameters such as material stiffness modulus and Poisson’s ratio. This research proposes a dynamic material failure model, which combines the three-parameter failure criterion proposed by Menetrey and Willam with the cap model proposed by Balan et al. to form the Close-Menetrey-Willam model. The dynamic failure model is expanded by the DIF (Dynamic Increase Factor). The dynamic failure model under different strain rate loading states is established, and the stress state at different moments on the dynamic material failure model to define the ultimate strength parameters at the current moment. Using the uniaxial stress-strain model proposed by Saenz, this formula only needs to define the ultimate strength parameters to describe the hardened and softened sections in concrete behavior. It is quite simple and convenient to use in numerical simulation. This study proposes a concrete deterioration model. The combination of the concrete deterioration strength formula proposed by Du Jian-min and the Close-Menetrey-Willam model, establishes a deterioration model with different damage levels, defines the ultimate strength parameters of deterioration model. The numerical examples in this study verify the high strain rate, low strain rate loading of concrete, low strain rate loading of ice, the low strain rate loading of ice at different temperatures and concrete deterioration.
WU, JIAN-HONG, i 吳建宏. "THE STUDY ON FAILURE CHARACTERISTIC OF MU-SHAN SANDSTONE UNDER UNIAXIAL STRESS". Thesis, 1998. http://ndltd.ncl.edu.tw/handle/25612553555492248281.
Pełny tekst źródłaHung, Pei Heng, i 洪培恒. "A Method to Apply Uniaxial Stress on Silicon Substrate at High Temperatures". Thesis, 2012. http://ndltd.ncl.edu.tw/handle/55157011718544499917.
Pełny tekst źródła長庚大學
電子工程學系
100
In this study, the effect of strain on USJs was studied. A method was developed to apply uniaxial stress on silicon substrate at high temperatures for ultra-shallow junctions (USJs). Polished (001) Si wafers with a thickness of 50 μm were cleaved along (110) directions into strips with a dimension of 18 mm × 3 mm. Stress was applied by bending and inserting the strips into slots in a u-shape quartz tray. After furnace process was finished, the sample curvature was measured. The stress on the sample was released then cut into small square pieces for Hall measurement. The influence of stress on was studied. Solid phase epitaxial regrowth (SPER). The specimens were prepared by Ge preamorphization implantation (PAI) and coimplantation with carbon and phosphorous. The samples with PAI were bending and annealed to cause SPER. Tensile stress increases the sheet concentration, but decreases the mobility. This leads to a higher sheet resistance. The experiment for deactivation annealing was performed with phosphorus USJ samples which had been activated by laser annealing. The samples were bended and annealed at low temperature for deactivation. Carrier concentration increases and the mobility decrease due to tensile stress. The trend of sheet concentration and mobility was both observed in SPER and deactivation experiments.
chien, Hsu-Wei, i 徐維謙. "Flow stress characteristics of magnesium alloy AZ31B-O thin sheet during Uniaxial tension". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/71067225130531681143.
Pełny tekst źródła中華大學
機械工程學系碩士班
97
The magnesium alloy has been used in Aerospace industry in 30’ due to its distinguish feature of light weight with high specific stiffness. However, the high cost of refining limited its application. In recent years, the electronic industry has gradually increased the usage of the Mg alloys for 3C products. Many electronic products, such as cell phone and notebook, use a great quantity of Mg alloys as the case materials. The Mg alloys can also play as the substitutional materials for ferroalloys and Al alloys, revealing the increasing needs of the Mg alloy. The main purpose of this paper is to explore the flow behavior of AZ31B-O Mg alloy thin sheet under uniaxial tension at different temperatures and strain rates. The values of strain hardening exponent n, strain rate sensitivity exponent m, and strength coefficient k based on the approximation of the Backofen formula were calculated form the stress-strain curves obtained from the tensile test results. Quantitative analysis was performed to investigate the effects of temperatures and strain rates on the mechanical properties and deformation characteristics of AZ31B Mg alloy. Experimental results showed that the 0° samples exhibited the largest elongation to failure for testing at temperatures of room temperature and 250°C. While the largest elongations to failure were observed in the 45° samples for testing at the temperatures of 300°C, 370°C and 420°C, the maximum tensile strengths were found in the 90° specimens. Under all test conditions, The maximum elongation to failure of 270% was obtained in the 45° sample for testing at a strain rate of 4×10-3 s-1 and at a temperature 420°C. The characteristics of the stress-strain cures at elevated temperatures are different from that of at room temperature. The stress-strain curves with serrations were found at elevated temperatures. Theses results were resulted from dynamic recrystallization during deforming the alloy at elevated temperatures. Dynamic recrystallization would cause softening effect resulting in the decrease in the flow stress and the rate of work-hardening. The softening effect would increase elongation to failure, necking in the test sample could be apparently observed for AZ31B Mg alloy tested at elevated temperatures. Calculated flow stress based on the Backofen formula was quite consistent with the tensile test results at room temperature. Since softening effect was not taken into account in this analysis, the calculated results at elevated temperatures only consisted with the experimental data before necking took place.
Jiratatprasot, Pornchai. "Mechanical properties and stress-strain behavior of high performance concrete under uniaxial compression". Thesis, 2002. http://library1.njit.edu/etd/fromwebvoyage.cfm?id=njit-etd2002-005.
Pełny tekst źródłaLee, Chih-Haw, i 李志浩. "Studies on Electrical Properties and Terahertz Absorption Spectrum of p-Ge under uniaxial stress". Thesis, 2009. http://ndltd.ncl.edu.tw/handle/33967337599391835205.
Pełny tekst źródła國立交通大學
電子工程系所
97
In this study, we measured the I-V and absorption characteristics of strained Ge:Ga samples at cryogenic temperature (10 K). As the stress increases along the [100] and [110] direction, the breakdown voltage increases to a maximum around 0.5-1 kBar and then decreases. The absorption spectra show that the energy differences between the ground states and the excited states also increase to a maximum then decrease in the same stress region. According to these results, we can propose a mechanism to explain the stress dependence of breakdown voltage. Our experiment is in agreement with the theoretical predictions.
Chia-JungHsu i 許嘉容. "Numerical analysis on the uniaxial compression stress-strain curves of hollow sphere foams between rigid plates". Thesis, 2017. http://ndltd.ncl.edu.tw/handle/tqm8tq.
Pełny tekst źródła國立成功大學
土木工程學系
105
Lightweight foam is a special kind of material with high porosity, good thermal insulation and excellent energy absorption. Foam has been widely used in lightweight structural engineering. However, due to the limitation in manufacturing, there are a variety of microstructural defects in commercially-available foams, thus reducing their engineering properties. In practice, hollow sphere foams are employed to replace the traditional foams with some microstructural defects resulting from production process. Because of the regularly-stacking microstructure of hollow sphere foams, their physical and engineering properties can be predicted more accurately. In the study, the difference in the uniaxial compressive stress-strain curves between the single-sized and dual-sized hollow sphere foams with the same relative density is discussed in detail. The commercially available finite element software ABAQUS is utilized here to conduct a series of numerical analyses. The stress-strain curves of hollow sphere foams between two rigid plates under uniaxial compression are obtained numerically. In running numerical analysis, a prescribed displacement is imposed on the rigid plates, the corresponding stresses on hollow sphere foams are calculated numerically. Furthermore, the resulting stress-strain curves of hollow sphere foams are presented and then compared to evaluate the effects of relative density and cell geometry. Numerical results show that the Young's modulus, yield strength and strain energy of dual-sized hollow sphere foams are consistently larger than those of single-sized hollow sphere foams with the same relative density.
Ching-YaoChang i 詹晴堯. "Temperature Dependence of Electrical Characteristic on the Uniaxial Tensile Strained CMOSFETs by Using Stress Memorization Technique (SMT)". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/05511007046809980601.
Pełny tekst źródłaHutcherson, Shawn Curtis. "Analysis of a database of uniaxial geogrid pullout resistance results". 2012. http://hdl.handle.net/2152/20050.
Pełny tekst źródłatext
Ghosh, Shreenanda. "Manipulation of time reversal symmetry breaking superconductivity in Sr₂RuO₄ by uniaxial pressure". 2021. https://tud.qucosa.de/id/qucosa%3A76124.
Pełny tekst źródłaLU, YU-YING, i 陸昱縈. "Investigation into Electrical Characteristics of Uniaxial Tensile Strained nMOSFETs by Using Stress Memorization Technique with Different SiN Film Thickness". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85496588211706000434.
Pełny tekst źródła正修科技大學
電子工程研究所
101
In this dissertation, the electrical characteristics of uniaxial tensile strained nMOSFETs were investigated, including DC characteristics and low-frequency (1/f ) noise. The strained nMOSFETs were fabricated by using stress memorization technique (SMT) with different thickness of tensile SiN film. Through series DC measurements, it found that SMT process-induced stress is truly transmitted from the deposited SiN layer, resulting in improved drive current stemming from enhanced carrier mobility. For 1/f noise measurement, as devices have more tensile stress, the decrease in 1/f noise can be observed. These results indicated the intrinsic benefit of uniaxial stained nMOSFETs. Consequently, based on these experimental results, optimal thickness of SiN film was also demonstrated.
Chia-ChiehHung i 洪佳杰. "Uniaxial Ratcheting of Sn/3.5Ag Solder Induced by Cyclic Shear Strain with Constant Tensile Stress–Investigation by Endochronic Cyclic Plasticity". Thesis, 2011. http://ndltd.ncl.edu.tw/handle/23331969364055991341.
Pełny tekst źródłaHartig, Jens. "Numerical investigations on the uniaxial tensile behaviour of Textile Reinforced Concrete". Doctoral thesis, 2010. https://tud.qucosa.de/id/qucosa%3A25532.
Pełny tekst źródłaDie vorliegende Arbeit beschäftigt sich mit Untersuchungen zum einaxialen Zugtragverhalten von Textilbeton. Textilbeton ist ein Verbundwerkstoff bestehend aus einer Matrix aus Feinbeton und einer Bewehrung aus Multifilamentgarnen aus Hochleistungsfasern, welche zu textilen Strukturen verarbeitet sind. Die Untersuchungen konzentrieren sich auf Bewehrungen aus alkali-resistentem Glas. Das Tragverhalten des Verbundwerkstoffs ist komplex, was aus der Heterogenität der Matrix und der Garne sowie der unvollständigen Durchdringung der Garne mit Matrix resultiert. Das Hauptziel der Arbeit ist die theoretische Untersuchung von Effekten und Mechanismen innerhalb des Lastabtragverhaltens von Textilbeton, welche nicht vollständig anhand verfügbarer experimenteller Ergebnisse erklärt werden können. Das entsprechende Modell zur Beschreibung des Zugtragverhaltens von Textilbeton soll verschiedene experimentelle Versuchstypen mit einem einheitlichen Modell abbilden können. Unter Vernachlässigung von Querdehneffekten wurde ein eindimensionales Modell entwickelt und im Rahmen der Finite-Elemente-Methode numerisch implementiert. Es werden jedoch auch Lastabtragmechanismen in Querrichtung durch eine Unterteilung der Bewehrungsgarne in sogenannte Segmente berücksichtigt. Das Modell enthält zwei Typen von finiten Elementen: Stabelemente und Verbundelemente. In Längsrichtung werden Stabelemente kettenförmig angeordnet, um das Tragverhalten von Matrix und Bewehrung abzubilden. In Querrichtung sind die Stabelementketten mit Verbundelementen gekoppelt. Das Modell erhält seine Komplexität hauptsächlich aus Nichtlinearitäten in der Materialbeschreibung, z.B. durch begrenzte Zugfestigkeiten von Matrix und Bewehrung, Zugentfestigung der Matrix, Welligkeit der Bewehrung und nichtlineare Verbundgesetze. Neben einer deterministischen Beschreibung des Materialverhaltens beinhaltet das Modell auch eine stochastische Beschreibung auf Grundlage eines Zufallsfeldansatzes. Mit dem Modell können Spannungsverteilungen im Verbundwerkstoff und Eigenschaften der Betonrissentwicklung, z.B. in Form von Rissbreiten und Rissabständen untersucht werden, was in dieser Kombination nur mit wenigen der existierenden Modelle für Textilbeton möglich ist. In vielen der vorhandenen Modelle sind diese Eigenschaften Eingangsgrößen für die Berechnungen und keine Ergebnisse. Darüber hinaus kann anhand des Modells auch das sukzessive Versagen der Bewehrungsgarne studiert werden. Das Modell wurde auf drei verschiedene Versuchstypen angewendet: den Filamentauszugversuch, den Garnauszugversuch und Dehnkörperversuche. Die Berechnungsergebnisse zu den Filamentauszugversuchen zeigten eine gute Übereinstimmung mit experimentellen Resultaten. Zudem wurden Parameterstudien durchgeführt, um Einflüsse aus Geometrieeigenschaften wie der eingebetteten und freien Filamentlänge sowie Materialeigenschaften wie dem Verbund zwischen Matrix und Filament zu untersuchen. Die Berechnungsergebnisse zum Garnauszugversuch demonstrierten die Anwendbarkeit des Modells auf diesen Versuchstyp. Es wurde gezeigt, dass für eine realitätsnahe Abbildung des Versagensverhaltens der Bewehrungsgarne eine relativ feine Auflösung der Bewehrung notwendig ist. Die Berechnungen lieferten die Verteilung von Versagenspositionen in der Bewehrung und die Entwicklung der Degradation der Garne im Belastungsverlauf. Ein Hauptziel der Arbeit war die Untersuchung von Effekten im Zugtragverhalten von Textilbeton, die bisher nicht durch experimentelle Untersuchungen erklärt werden konnten. Daher wurde eine Vielzahl von Parameterstudien zu Dehnkörpern mit mehrfacher Matrixrissbildung, welche das Zugtragverhalten von Textilbeton ähnlich praktischen Anwendungen abbilden, durchgeführt. Die Berechnungsergebnisse zeigten, dass der experimentell beobachtete dreigeteilte Verlauf der Spannungs-Dehnungs-Beziehung von Textilbeton bestehend aus dem ungerissenen Zustand, dem Zustand der Matrixrissbildung und dem Zustand der abgeschlossenen Rissbildung vom Modell wiedergegeben wird. Die beste Übereinstimmung zwischen berechneten und experimentellen Ergebnissen ergab sich unter Einbeziehung von Streuungen in den Materialeigenschaften der Matrix, der Zugentfestigung der Matrix und der Welligkeit der Bewehrung.
Bochmann, Jakob. "Carbonbeton unter einaxialer Druckbeanspruchung". 2019. https://tud.qucosa.de/id/qucosa%3A35075.
Pełny tekst źródłaNg, Evelyn. "Strengthening Mechanisms in Microtruss Metals". Thesis, 2012. http://hdl.handle.net/1807/34825.
Pełny tekst źródłaBaumgarten, Lars. "Gesteinsmechanische Versuche und petrophysikalische Untersuchungen – Laborergebnisse und numerische Simulationen". Doctoral thesis, 2015. https://tubaf.qucosa.de/id/qucosa%3A23031.
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