Dissertations / Theses: 'Shear deformation'

1

Attfield, Peter Richard. "Mechanisms of shear zone deformation." Thesis, Keele University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253688.

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2

Brabham, Kori Vasser. "THE EFFECTS OF SHEAR DEFORMATION ON CHONDROGENESIS." MSSTATE, 2004. http://sun.library.msstate.edu/ETD-db/theses/available/etd-06252004-150210/.

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Due to mechanical loading, cartilage experiences distortional change, volumetric change, and fluid flow. Research has shown cells to be responsive to unconfined compression, a load that produces all three conditions. To isolate the factor(s) responsible for chondrogenesis, the first goal of this research was to design and implement a device for the application of shear deformation to cells. Secondly, using this device, Stage 23/24 chick limb bud cells were suspended in 2% alginate and subjected to 20% shear deformation at 1 Hz. for two hours daily for three days. Gene expression, DNA content, sGAG content, and cartilage nodule formation were determined after eight days in culture and compared to results obtained for non-loaded cells. Results indicated that shear deformation at the applied level did not have a significant effect on chondrogenesis in Stage 23/24 chick limb bud cells, suggesting that this cell type is not extremely sensitive to distortional change.

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3

Qureshi, Farrukh Shahab. "Kinematics of shear deformation of materials under high pressure and shear stress." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/18841.

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4

Student, James John. "The Box Ankle and Ocmulgee shear zones of central Georgia: a study of geochemical response to Southern Appalachian deformation events." Thesis, This resource online, 1992. http://scholar.lib.vt.edu/theses/available/etd-09192009-040411/.

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5

De, Magistris Federica. "Wood fibre deformation in combined shear and compression." Doctoral thesis, KTH, Mekanik, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-415.

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Mechanical pulping for producing pulps from softwood suitable for printing grade papers, like news, is a highly energy-intensive process consuming around 2000 kWh/t in electrical energy. Due to increasing energy costs and environmental issues there is a high demand for decreasing this energy consumption. The mechanical treatment of wet wood pieces in a refiner, in the mechanical pulp plant, is a complex mechanical loading. This is a process occurring between rotating discs at high speed and temperatures of 140 °C - 160 °C, where by means of shear and compression forces the fibres are separated and then made flexible, fibrillated and collapsed for good bonding ability. In this process also fines are created giving the optical properties of the paper. In mechanical pulping only a fraction of the applied energy is used for the structural changes of the wood material. Thus fundamental studies of the loading modes of wood under refining conditions and in particular under combined shear and compression loading are desired to gain more information regarding the possibility of affecting the mechanical pulping in an energy efficient way. The possibilities to study the behaviour of wood under a combined shear and compression load were in this thesis investigated using two methods: the Iosipescu shear test and the Arcan shear test. In both apparatus different combinations of shear and compression load were achieved by different rotations of the shear test device itself. Measurements with the Iosipescu device on a medium density fibreboard showed good agreement between experimental results and numerical simulations. Finite element analysis on wood showed, however, that with the use of a homogeneous material in the model the level of strain reached would be ten times smaller than experimentally measured. This fact is probably due to the honeycomb structure of the wood cells that allows for different local deformations that could not be represented by a continuous material model. Thus to study the deformations on the fibre level of wood an experimental equipment that uses smaller samples was needed. With a modified Arcan shear device such deformations under combined shear and compression load and in pure compression were possible showing different deformation patterns. During pure compression the cell walls bend in a characteristic “S” shape, independently of the shape of the fibre cells and their cell wall thickness. Under combined shear and compression, however, mainly the corners of the fibre cells deform giving a “brick” shape to the cells. In a second deformation performed in compression, the fibre cells follow the same deformation pattern as given by the first deformation type whether in compression or in combined shear and compression. The interpretation is that permanent defects in the cells themselves are introduced already in the first load cycle of the wood samples. The energy used under the different loading conditions showed that the first deformation required the largest amount of energy, for all loading conditions. The deformation in compression required larger amounts of energy than the deformation in combined loads. For subsequent deformations less energy was needed for compression if a combined load had preceded it. Due to the fact that less energy is needed to start to deform wood in combined load than under compression load, the application of a combined load as a first cycle may thus be a way to permanently deform fibres using less energy. To investigate the critical parameters determining the permanent deformation of cells, a finite element model of a network of twelve cells was developed. Special care was given to the material properties to study how the variation of the fibril angle in the different layers affects the deformation pattern of the wood fibres under the different loading conditions. The model shows that whether modelled as homogeneous linear isotropic material or as an orthotropic material defined for every layer of the cells wall, no difference in the deformation of the network of the fibres was achieved. It is probable that the deformation type is more determined by the geometry of the fibres themselves than by their material properties
QC 20101005

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6

Magistris, Federica De. "Wood fibre deformation in combined shear and compression /." Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-415.

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7

Zhang, Xu. "DEFORMATION AND SHEAR BEHAVIORS OF WEATHERED COMPACTED SHALE." UKnowledge, 2014. http://uknowledge.uky.edu/ce_etds/23.

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As an abundant sedimentary rock, shale is widely used as construction material around the world. However, shale is a fissile and laminated material and is therefore subject to deterioration due to environmental and chemical forces (i.e., weathering), which is possible to cause high maintenance cost on associated structures and failures of earth slopes and embankments. However, currently, there is lack of efficient method to monitor the weathering process of shale. This thesis uses several shale samples collected from the commonwealth of Kentucky to study the deformation and shear behaviors of weathered compacted shale. A new electrical approach was developed to access the deformation behavior of shale. The long term deformation behaviors, such as collapse and swell can be predicted from specific electrical parameters. The critical state theory was used to describe the shear behavior of weathered compacted shale. Some findings observed by previous researchers were confirmed, and new empirical equations were provided to estimate the shear strength parameters of weathered compacted shale.

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8

Abu-Saman, Awni. "Large plastic deformation and shear localization of crystals." Doctoral thesis, University of Cape Town, 2000. http://hdl.handle.net/11427/4954.

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9

Watts, Robert James. "The laboratory simulation of subglacial sediment deformation." Thesis, University of Southampton, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.243164.

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10

Ahmad, M. K. M. "Shear lag effect in composite box girders." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237869.

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11

Peacock, Sheila. "Shear-wave splitting in the Earth's crust." Thesis, University of Edinburgh, 1986. http://hdl.handle.net/1842/15614.

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12

Malvick, Erik Jon. "Void redistribution-induced shear localization and deformation in slopes /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.

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13

Moore, Margaret Anne. "Crustal deformation in the southern New Zealand region." Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.325829.

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14

Murphy, Justin James. "Kinematics, partitioning and the relationship between velocity and strain in shear zones." Online access for everyone, 2007. http://www.dissertations.wsu.edu/Dissertations/Summer2007/j_murphy_061907.pdf.

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15

PETROVIC, Mario. "Wrinkle generation mechanism in flat and cylindrical membranes undergoing shear deformation." 京都大学 (Kyoto University), 2015. http://hdl.handle.net/2433/199271.

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16

Godbille, Frédéric Dominique. "Drop deformation and break-up in combined shear and extensional flows." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0026/MQ38377.pdf.

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17

Islam, MD Zahurul. "Normalised undrained shear strength and deformation properties of remoulded Keswick clay /." Title page, abstract and table of contents only, 1994. http://web4.library.adelaide.edu.au/theses/09ENS/09ensi82.pdf.

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18

Godbille, Frederic Dominique. "Drop deformation and break-up in combined shear and extensional flows." Thesis, University of New Brunswick, 1998. http://hdl.handle.net/1882/902.

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19

Gottlander, Johanna. "Small-Scale Shear Zones and Deformation in Migmatite on Mt. Åreskutan." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-260958.

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The Åreskutan nappe complex consists of the partly molten rock migmatite, which originates from the subduction formed by the collision of continents Baltica and Laurentia. It is a so-called hot nappe, which has been deeply buried in the subduction zone, based on findings of high-pressure minerals in the migmatitic gneiss. As the nappe returned to shallower depths the rock was partially molten during the subsequent exhumation as the lithostatic pressure decreased. Tectonic forces led to thrusting of the nappe towards the east and the building of mount Åreskutan. It is generally accepted that the shear zone between the migmatite of the Åreskutan Nappe and the underlying Lower Seve Nappe is a mylonitic shear zone, but the question of whether similar shear zones can be found at other sites in the migmatite complex has now been raised. In this project two major shear zones have been identified and shear direction has been determined after detailed geological mapping. Many small shear zones have also been identified, but their sense of shear direction was more difficult to determine. The two major shear zones identified have been labelled the Eastern Major Shear Zone and Western Major Shear Zone. In these shear zones the original migmatite appearing on Åreskutan is deformed and sheared with a top to the east sense of shear. The strongest evidence for determining the shear sense are garnets found mantled by micas in a sigma-type shear microstructures, found during microscope analysis. A grade of mylonitization can be seen in the mineral microstructures, with the most fine-grained matrix in the centre of the shear zones. It indicates that ductile deformation dominates, even though some minerals tend to break in a brittle manner.

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20

Gandy, David R. "Shear deformation of amorphous and nanocrystalline copper microstructures via atomistic simulation." Thesis, Massachusetts Institute of Technology, 2007. http://hdl.handle.net/1721.1/40424.

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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2007.
Includes bibliographical references (p. 24).
In the well-known Hall-Petch behavior, yield and flow stresses in polycrystalline metals increase with a decrease in grain size. As grain size continues to decrease, mechanical strength peaks. As grain size further decreases, mechanical strength begins to decrease. As grain size approaches zero, the total structure is composed of an increasingly high percentage of grain boundaries, which exhibit the properties of an amorphous structure. Molecular dynamics simulations, with the goal of exploring this behavior, were performed on nanocrystalline and amorphous microstructures using the embedded atom potential developed by Mishin et al. A 0.2 shear strain was applied to each of the nanocrystalline and amorphous samples. From these simulations, we have observed the inverse Hall-Petch behavior of nanocrystalline structures. We have also shown that the amorphous structure as zero grain size is reasonable as the limiting case for the inverse Hall-Petch trends in nanocrystalline structures.
by David R. Gandy.
S.B.

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21

Blank, V. D., A. N. Kirichenko, A. K. Aseev, V. N. Denisov, I. A. Perezhogin, B. A. Kulnitskiy, and A. A. Nuzhdin. "Influence of Shear Deformation on Carbon Onions Stability under High Pressure." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35018.

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The influence of shear deformation on carbon onions stability under high pressure up to 45 GPa was investigated in a Shear Diamond Anvil Cell (SDAC) by the Raman spectroscopy and the Transmission Electron Microscopy (TEM). At shear less then 40 degrees the carbon onions are stable up to 30 GPa. Biger shear deformation leads to increasing of size and destruction of the onions and to formation of sp3 C-C bonds. At pressure exceeded 45 GPa shear deformation leads to diamond-like carbon (DLC) formation. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35018

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22

Iyer, Hariharan. "The Effects of Shear Deformation in Rectangular and Wide Flange Sections." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31421.

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Shear deformations are, generally, not considered in structural analysis of beams and frames. But shear deformations in members with low clear span-to-member depth ratio will be higher than normally expected, thus adversely affecting the stiffness of these members. Inclusion of shear deformation in analysis requires the values of shear modulus (modulus of rigidity, G) and the shear area of the member. The shear area of the member is a cross-sectional property and is defined as the area of the section which is effective in resisting shear deformation. This value is always less than the gross area of the section and is also referred to as the form factor. The form factor is the ratio of the gross area of the section to its shear area. There are a number of expressions available in the literature for the form factors of rectangular and wide flange sections. However, preliminary analysis revealed a high variation in the values given by them. The variation was attributed to the different assumptions made, regarding the stress distribution and section behavior. This necessitated the use of three-dimensional finite element analysis of rectangular and wide flange sections to resolve the issue.

The purpose of finite element analysis was to determine which, if any, of the expressions in the literature provided correct answers. A new method of finite element analysis based on the principle of virtual work is used for analyzing rectangular and wide flange sections. The validity of the new method was established by analyzing rectangular sections for which closed form solutions for form factor were available. The form factors of various wide flange sections in the AISC database were calculated from finite element analysis and an empirical relationship was formulated for easy calculation of the form factor. It was also found that an empirical formula provided good results for form factors of wide flange sections.

Beam-column joint sub-assemblies were modeled and analyzed to understand the contribution of various components to the total drift. This was not very successful since the values obtained from the finite element analysis did not match the values calculated using virtual work. This discrepancy points to inaccuracies in modeling and, possibly, analysis of beam-column joints. This issue needs to be resolved before proceeding further with the analysis.
Master of Science

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23

McGibbon, David. "Shear zones of the Maud Belt, Antarctica : kinetics and deformation mechanisms." Master's thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/9607.

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Includes bibliographical references.
The rocks of the Maud Belt, western Dronning Maud Land, Antarctica, have experienced at least two deformation phases related to the Grenvillian and Pan- African orogenies. Deformation is heterogeneous and strain is commonly localized within shear zones. The two study areas H.U. Sverdrupfjella and Neumayerskarvet mainly consist of paragneisses and orthogneisses and in places migmatites and granite intrusions. The orthogneisses and paragneisses mainly consist of coarse to medium grained quartz, feldspar and biotite and in places hornblende, garnet and epidote. The rock types only differ in the proportion of these minerals, the paragneisses having a higher proportion of biotite than the orthogneisses. Both study areas contain well developed lineations, defined by elongated quartz grains and in places hornblende and epidote, and a S₁+₂ foliation defined by biotite. The foliation is related to the shear zones in the region which are commonly sub-horizontal but locally sub-vertical in eastern Neumayerskarvet. In eastern Neumayerskarvet the paragneisses wrap around the competent orthogneiss units, resulting in sub-vertical strike-slip shear zones alongside the competent orthogniess units. Two differently orientated lineations are found in the study areas, a weak, shallow plunging, E-trending lineation that occurs within the host rock and always alongside a well developed, shallow plunging, SE-trending lineation. Within the shear zones only the SE-trending lineation is found. The presence of only the SE-trending lineation in the shear zones implies that the SE-trending lineation is associated with a more recent deformation phase, D₂, and that the weak Etrending lineation is associated with an older deformation phase, D₁. Two major collisional events affected the region, the Grenvillian (~1300 Ma to ~900 Ma) and the Pan-African (~600 Ma to ~450 Ma). D₂ is therefore likely associated with the Pan-African orogeny and D₁ with the older Grenvillian orogeny. Evidence for D₁ is distributed broadly within the host rock and is absent from the shear zones. If D₁ localized shear zones did exist, they have been overprinted by D₂. The presence of only D₂ in the shear zones implies that strain in D₂ was localized. The strain partitioning into narrow shear zones during the more recent deformation phase could be due to pre-existing fabrics from an earlier deformation phase. Superposition of later deformation into zones of pre-existing fabrics could be typical of areas that have experienced multiple deformation phases.

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24

Nagappan, Govindan. "Analysis of composite moving beams using higher order shear deformation theory." Morgantown, W. Va. : [West Virginia University Libraries], 2004. https://etd.wvu.edu/etd/controller.jsp?moduleName=documentdata&jsp%5FetdId=3463.

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Thesis (M.S.)--West Virginia University, 2004.
Title from document title page. Document formatted into pages; contains xi, 126 p. : ill. Includes abstract. Includes bibliographical references (p. 123-126).

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25

Lodhi, Muhammad S. "RESPONSE ESTIMATION OF REINFORCED CONCRETE COLUMNS SUBJECTED TO LATERAL LOADS." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1269631164.

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26

Jupe, Andrew John. "Induced microseismicity and the mechanical behaviour of jointed rock during the development of an HDR geothermal reservoir." Thesis, Open University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.254252.

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27

Carty, James. "Deformation, magmatism and metamorphism in the Portsoy shear zone, north-east Scotland." Thesis, University of Derby, 2001. http://hdl.handle.net/10545/200010.

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28

Pople, John. "Organized structures induced in polymeric and liquid crystalline systems by shear deformation." Thesis, University of Reading, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.308051.

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29

Al-Ubaidi, Haitham. "The influence of shear deformation on the behaviour of pultruded polymeric composites." Thesis, Cardiff University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324099.

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Pultruded, fibre reinforced, polymeric composites are now being used in a wide range of structural engineering applications, due to their high strength to weight ratios and resistance to environmental conditions. However, such materials posses a relatively low shear modulus in relation to their axial and flexural moduli. This can result in shear deformation constituting a significant proportion of the total deformation and a reduction in buckling loads for various modes of instability. An experimental and theoretical study of the influence of shear deformation on the flexural and torsional stiffnesses and various modes of instability of pultruded polymeric bars of open cross-section is therefore presented. Theories for the bending and warping torsional response of pultruded, fibre reinforced polymeric bars of open cross-section, excluding and including the influence of shear deformation, are presented. Full section bending mechanical properties of several pultruded beams are determined using a static testing apparatus and a wide variety of span configurations. Full section warping torsional mechanical properties of several pultruded bars are determined using a new testing apparatus, capable of applying a torque to any cross-section along a bar, whilst maintaining the bars lateral position. Theories for the flexural, torsional and lateral instability of pultruded, fibre reinforced polymeric bars of open cross-section, excluding and including the influence of shear deformation, are developed and presented. Parametric studies of the influence of shear deformation in the flexural, torsional and lateral instability of various pultruded bars of open cross-section are also presented. The experimental and theoretical studies indicate that shear deformation reduces significantly the non-uniform bending stiffness of pultruded polymeric bars, but that its influence on the non-uniform and restrained warping torsional stiffness is practically negligible. Shear deformation has also been found to result in a significant reduction in flexural, torsional and coupled flexural-torsional or lateral buckling loads.

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30

Shields, Jessica. "Shear deformation of highly viscous magmas : a textural study of strain localisation." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.686815.

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Whether silicic volcanoes erupt explosively or effusively is controlled by the ability of magma to lose gas prior to eruption. However the mechanisms behind permeability development and obsidian generation remain an enigma for volcanologists. Torsion experiments were performed at high temperature and pressure on three-phase rhyolitic magma analogues simulating magma deforming in shallow conduit conditions. Significant loss of porosity and dissolved water occurred due to brittle fracturing of the melt. Outgassing efficiency increases with strain and is enhanced by crystal content. Fabric development as a result of strain localisation impacts sample rheology as much as crystal, bubble or water contents. Experiments suggest multiple fractures must have formed and healed during shear to account for observed water loss. Viscous suspensions of particles and bubbles were sheared to observe, in real time, the development of deformation fabrics. Bubble deformation and crystal rearrangement are enhanced by increasing crystal content and strain-rate, which magnify heterogeneities in distributions of particles and the gas phase. Development of bands of high particle content and low strain adjacent to melt-rich, high strain areas illustrate the first stage in the formation of permeable outgassing networks and reveals the governing role of textures on magma rheology and outgassing. Multiple methods were used to study outgassing and emplacement mechanisms of the Rocche Rosse obsidian flow. Strain localisation and highly localised variations in melt water content are responsible for extreme textural heterogeneity observed on micron to m scale in the flow. The formation of repeated flow bands may result from high sensitivity of obsidian degassing to water content. Complex surface deformation as opposed to conduit processes governs water and textural distribution and prolongs flow. A model is proposed consisting of multiple cycles of shear-induced outgassing, densification and re-vesiculation during ascent and emplacement to result in observed textures and water contents.

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31

Oygur, Ozgur Sinan. "Semi Analytical Study Of Stress And Deformation Analysis Of Anisotropic Shells Of Revolution Including First Order Transverse Shear Deformation." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609870/index.pdf.

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In this study, anisotropic shells of revolution subject to symmetric and unsymmetrical static loads are analysed. In derivation of governing equations to be used in the solution, first order transverse shear effects are included in the formulation. The governing equations can be listed as kinematic equations, constitutive equations, and equations of motion. The equations of motion are derived from Hamilton&rsquo
s principle, the constitutive equations are developed under the assumptions of the classical lamination theory and the kinematic equations are based on the Reissner-Naghdi linear shell theory. In the solution method, these governing equations are manipulated and written as a set called fundamental set of equations. In order to handle anisotropy and first order transverse shear deformations, the fundamental set of equations is transformed into 20 first order ordinary differential equations using finite exponential Fourier decomposition and then solved with multisegment method of integration, after reduction of the two-point boundary value problem to a series of initial value problems. The results are compared with finite element analysis results for a number of sample cases and good agreement is found. Case studies are performed for circular cylindrical shell and truncated spherical shell geometries. While reviewing the results, effects of temperature and pressure loads, both constant and variable throughout the shell, are discussed. Some drawbacks of the first order transverse shear deformation theory are exhibited.

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32

Nekouie, Vahid. "Deformation behaviour of a Zr-Cu-based bulk metallic glass." Thesis, Loughborough University, 2017. https://dspace.lboro.ac.uk/2134/25246.

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While inelastic mechanical behaviour of crystalline materials is well-understood in terms of lattice defects, bulk metallic glasses (BMGs) pose significant challenges in this respect due to their disordered structure. They can be produced by rapid cooling from the liquid state (among other technique) and, thus can be frozen as vitreous solids. Due to the absence of a long-range order in atomic structure and a lack of defects such as dislocations, BMGs generally show unique mechanical properties such as high strength and elastic limit, as well as good fracture toughness and corrosion resistance. Typically, inorganic glasses are brittle at room temperature, showing a smooth fracture surface as a results of mode-I brittle fracture. At small scale, it was well documented that inelastic deformation of bulk metallic glasses is localised in thin shear bands. So, in order to understand deformation mechanisms of BMGs comprehensively, it is necessary to investigate formation of shear bands and related deformation process. In this thesis, a history of development of BMGs is presented, followed by a review of fundamental mechanisms of their deformation.

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33

Cullen, Daniel Kacy. "Response of neurons cultured in two-and-three-dimensions to dynamic shear deformation." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/17520.

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34

O'Connor, Bernard. "High strain deformation and ultimate failure of HIPS and ABS polymers." Thesis, Cranfield University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.245417.

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35

Zhao, Pengyang. "Mesoscale modeling of mechanical deformation of metallic glasses." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1417961426.

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36

Viforr, Silvia. "A way of reducing the energy demand in TMP by shear/compression deformation." Licentiate thesis, Stockholm : Department of Polymer Technology, Royal Institute of Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4282.

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37

Boyer, Robert D. (Robert Damian) 1978. "Shear-induced homogeneous deformation twinning in FCC aluminum and copper via automistic simulation." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17035.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2003.
Includes bibliographical references (leaves 77-80).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The {111}<112̄> shear stress-displacement behavior for face-centered cubic (fcc) metals, aluminum and copper, is calculated using empirical potentials proposed by Mishin and by Ercolessi, based on the embedded atom method (EAM), and compared with published ab initio calculations. In copper close agreement is observed in the results given by the Mishin potential for both the ideal shear strength and local atomic relaxation during shear, although the extent of plastic deformation before failure is over-predicted. In aluminum, both the Mishin and Ercolessi potentials are used, with only the former able to capture the majority of the behavior exhibited in first principle calculations. Both potentials are shown to have difficulties modeling the effects of directional bonding. Calculations of the multiplane generalized stacking fault energy in both materials reveal that aluminum has a longer range of atomic interaction than copper. Using molecular dynamics and static energy calculations, deformation twins are shown to form by homogeneous nucleation, slip and subsequent coalescence of partial dislocations in both copper and aluminum. The minimum energy path for formation of a two-layer microtwin, and the energy barriers to its further growth are analyzed for the two metals. The mechanism observed is interpreted with reference to existing work on the nucleation of microtwins in body-centered cubic metals.
by Robert D. Boyer.
S.M.

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38

Jin, Moonsoo 1971. "Chondrocyte metabolism and matrix nano-electromechanics : the response to cartilage tissue shear deformation." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8328.

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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2002.
Includes bibliographical references (leaves 160-171).
Cartilage functions as a load bearing and friction reducing material in synovial joints and it is constantly exposed to in vivo loading which is coupled to electromechanical and physicochemical forces. The swelling pressure of cartilage originates from proteoglycans containing negatively charged carboxyl and sulfate groups within glycosaminoglycans. Proteoglycans are embedded within the network of collagen fibrils whose molecular structure (supercoiled helix of three alpha-chain subunits) provides resistance to tensile forces, and contributes to the overall poroviscoelastic behavior of the tissue. The dynamic balance between repulsive and tensile forces gives cartilage unique compressive and shear stiffness that varies with the rate of deformation. Chondrocytes synthesize and degrade matrix components influenced by the regulatory signals present in the extracellular matrix. The transduction mechanisms by which mechanical signals are converted to a biological response are not completely understood. Therefore, the knowledge of both biological and biophysical aspects of cartilage is important to understand the dynamic interaction between the cells and matrix. In this study, the electromechanical properties of cartilage have been studied by measuring equilibrium and dynamic shear stiffness as a function of the ionic concentration of bath solution. Measured shear properties were dependent on ionic concentration; the shear modulus increased and the phase angle between stress and strain decreased with decreasing ionic concentration.
(cont.) Theoretical models were developed to interpret the experimental results: 1) the glycosaminoglycans (GAGs) were modeled as cylindrical rods (a unit cell model) with the geometry based on the experimental measurement; 2) GAGs were embedded within collagen network which supports the repulsive forces between GAGs; 3) macroscopic shear deformation was reflected on the randomly oriented unit cell; and 4) the Poisson-Boltzmann equation was used to calculate the change in the free energy and the shear modulus as a function of ionic concentration and shear deformation. The reasonable comparison between experimental results and theoretical calculations suggests that the microstructural rearrangement of GAGs during shear deformation is an important determinant in the shear stiffness of cartilage. In vivo compression of cartilage influences chondrocyte biosynthesis through mechanical deformation, fluid flow, and concomitant electrical and physicochemical changes. In vitro systems utilizing one or a combination of biophysical forces which chondrocytes are exposed to during compressive deformation in vivo have shown the complexity of biophysical environment, which potentially could alter chondrocyte biosynthesis. In this study, we have hypothesized that 1) shear deformation on poroelastic tissue like cartilage does not induce pressure gradient and relative interstitial fluid motion and 2) cell-matrix deformation produced by tissue shear deformation, with little or no accompanying fluid flow, can regulate cartilage metabolism. For this purpose, we have developed an incubator-housed tissue loading apparatus that can mimic the shear deformation in vivo on cartilage explants ex vivo ...
by Moonsoo Jin.
Sc.D.

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39

Liu, Chorng-Fuh. "Geometrically nonlinear analysis of composite laminates using a refined shear deformation shell theory." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54453.

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The theory is based on an assumed displacement field, in which the surface displacements are expanded in powers of the thickness coordinate up to the third order. The theory allows parabolic description of the transverse shear stresses, and therefore the shear correction factors of the usual shear deformation theory are not required in the present theory. The theory accounts for small strains but moderately large displacements (i.e., von Karman strains). Exact solutions for certain cross-ply shells and finite-element models of the theory are also developed. The finite-element model is based on independent approximations of the displacements and bending moments (i.e., mixed formulation), and therefore only C°-approximations are required. Further, the mixed variational formulations developed herein suggest that the bending moments can be interpolated using discontinuous approximations (across inter-element boundaries). The finite element is used to analyze cross-ply and angle-ply laminated shells for bending, vibration, and transient response. Numerical results are presented to show the effects of boundary conditions, lamination scheme (i.e., bending-stretching coupling and material anisotropy) shear deformation, and geometric nonlinearity on deflections and frequencies. Many of the numerical results presented here for laminated shells should serve as references for future investigations.
Ph. D.

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40

Mitchell, Frances. "Structural analysis of brittle deformation features along Grenvillian shear zones in southeastern Ontario." Thesis, Kingston, Ont. : [s.n.], 2007. http://hdl.handle.net/1974/496.

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41

Chen, Hsi-Ching B. "Shear localization in high-strain-rate deformation of inert and reactive porous materials /." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 1997. http://wwwlib.umi.com/cr/ucsd/fullcit?p9732695.

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42

Hussain, Wasiq. "Propagation, reflection and transmission of plane waves in pre-stressed elastic solids." Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.326431.

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43

Mazza, Sarah Elizabeth. "Thermal Structure of Mid-Crustal Shear Zones." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23284.

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Analysis of quartz c-axis fabrics and microstructures from ductily deformed rocks allows for the examination of the kinematics associated with crustal deformation. This thesis expands on the current knowledge of the kinematic evolution of the Himalayas and Scottish Caledonides, by examining samples from the Main Central Thrust (MCT) (Himalayas) and the Sgurr Beag Thrust (SBT) (Scottish Caledonides). Metamorphic temperatures (Tm) associated above the MCT are inverted; chapter one attempts to test if deformation temperatures (Td) correlate to Tm, indicating that ductile shearing occurred during peak Tm. In the Scottish Caledonides, Td and Tm increase from foreland to hinterland, potentially indicating a right way up thermal structure; chapter two presents Td and Tm associated with the region around the SBT. Above the MCT, quartz c-axis fabrics yield Td ranging between 500-650 "C, corresponding to the temperatures of dynamic recrystallization for subgrain rotation (SGR) and grain boundary migration (GBM). Up to 1000m above the MCT, Td and Tm are within error of each other, suggesting that shearing occurred during peak Tm; while further away from the MCT Tm is significantly hotter than Td, suggesting that shearing continued past Tm. Deformation associated with the upper part of the Moine thrust sheet and the SBT yields quartz c-axis fabrics with Td ranging between 395-583 "C, corresponding to the regional dynamic recrystallization. Tm calculations original to this study yield pressure-temperature constraints of 4.8-5.8 kbar and 586-625 "C. Tm is within error of Td, suggesting that deformation and metamorphism were synchronous.
Master of Science

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44

Montz, William J. "Cretaceous partial melting, deformation, and exhumation of the Potters Pond migmatite domain, west-central Idaho." Thesis, Boston College, 2016. http://hdl.handle.net/2345/bc-ir:107195.

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Thesis advisor: Seth C. Kruckenberg
The Potters Pond migmatite domain (PPMD) is a heterogeneous zone of migmatites located ~10 km southwest of Cascade, Idaho within the western Idaho shear zone (WISZ). The PPMD is the only known exposure of migmatites within the WISZ over its ~300 km length, occurring where the shear zone orientation changes from 020° south to 000° north of the migmatite domain. Structural mapping within the PPMD has identified multiple generations of migmatite with varied structural fabrics. Leucosome layers were sampled from distinct migmatite localities and morphologies (e.g., metatexite, diatexite) to determine the timing and duration of partial melting in the PPMD. U-Pb age determinations of zircon by means of LA-ICP-MS document two periods of protracted migmatite crystallization during the Early and Late Cretaceous. Early Cretaceous (ca. 145 to 128 Ma) migmatite crystallization ages are coeval with the collision and suturing of oceanic terranes of the Blue Mountains province with North America, and the formation of the Salmon River suture zone (SRSZ). Migmatite crystallization ages from ca. 104 to 90 Ma are associated with Late Cretaceous dextral transpression in the WISZ. Field observations and geochronology of cross cutting leucosome relationships are interpreted to record deep crustal deformation and anatexis associated with formation of the SRSZ, subsequently overprinted by solid-state deformation and renewed anatexis during the evolution of the WISZ. These data are the first direct evidence of the synmetamorphic fabric related to the SRSZ east of the initial Sr 0.706 isopleth, and that the WISZ is a temporally distinct overprinting structure
Thesis (MS) — Boston College, 2016
Submitted to: Boston College. Graduate School of Arts and Sciences
Discipline: Earth and Environmental Sciences

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45

Harris, Matthew Bradley. "Elucidating the Mechanisms of Rate-Dependent Deformation at Ambient Temperatures in a Model Metallic Glass." BYU ScholarsArchive, 2015. https://scholarsarchive.byu.edu/etd/6145.

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In this work, the Shear Transformation Zone (STZ) dynamics model is adapted to capture the transitions between different regimes of flow serration in the deformation map of metallic glass. This was accomplished by scaling the STZ volume with a log-linear fit to the strain rate, and also adjusting the activation energy of an STZ with a log-linear fit to maintain constant yield strength at differing strain rates. Twelve simulations are run at each of six different strain rates ranging from 10-5 to 100 s-1, and statistics are collected on simulation behavior and shear band nucleation and propagation rates. The simulations show shear band nucleation has a positive correlation to strain rate, and shear band propagation has a negative correlation to strain rate. This shows that in STZ dynamics, the regime of reduced flow serration arises due to competing rates of nucleation and propagation, supporting the hypothesis proposed by Schuh. A positive correlation between critical shear band nucleus size and strain rate is proposed as an underlying cause of these rate dependencies.

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46

Nosier, Asghar. "On vibration and stability problems of laminated plates and shells using shear deformation theories." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/37868.

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This study deals with the vibration and stability analyses of laminated plates and shells, using classical, first-order and third-order equivalent single-layer theories and the layer-wise theory of Reddy. Analytical solutions of these theories for natural frequencies and critical buckling loads of plates and shells under various boundary conditions are developed using an improved analytical procedure. A solution for the transient response of viscously damped cross-ply laminated plates, subjected to a sonic-boom type loading, is developed using the third-order shear deformation plate theory of Reddy and the first-order shear deformation plate theory. The nonlinear dynamic equations of the first-order shear deformation plate theory and the third-order shear deformation plate theory of Reddy are reformulated in terms of a pair of equations describing the interior and the edge-zone problems of rectangular plates laminated of transversely isotropic layers. The pure—shear frequencies of the plate in linear and nonlinear problems are identified from the edge—zone equation. For certain boundary conditions the original system of equations are reduced to three in number, as in the classical plate theory. The frequency and buckling equations of symmetric plates laminated of transversely isotropic layers are obtained using the Levinson’s third—order shear deformation plate theory. Using the interior and the edge—zone equations, the frequency and buckling equations are also obtained according to the first—order shear deformation plate theory. The solution contribution of the edge—zone equation is analyzed. By introducing a mixed approach, the bending problem of laminated plates with various boundary conditions is studied according to the first—order and Reddy’s third-order shear deformation plate theories.
Ph. D.

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47

UEHARA, Takuya, Takato TAMAI, and Nobutada OHNO. "Molecular Dynamics Simulations of Shape-Memory Behavior Based on Martensite Transformation and Shear Deformation." The Japan Society of Mechanical Engineers, 2006. http://hdl.handle.net/2237/9014.

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48

Ahirwal, Deepak. "Large deformation shear and elongation rheology of polymers for electrospinning and other Industrial Processes." Phd thesis, Université de Strasbourg, 2013. http://tel.archives-ouvertes.fr/tel-01065971.

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The goals of this thesis are the characterization of polymer melts using mainly non-linear shear and extensional rheological techniques. The fabrication of scaffolds with excellent physical and mechanical properties using solution electrospinning technology for tissue engineering applications and the development of melt electrospinning equipment to facilitate the fabrication of solvent free scaffolds. To achieve the first goal, we focused on the characterization of entangled polymer melts in the linear and nonlinear viscoelastic regimes. The influence of molecular weight, Mw, molecular weight distribution (MWD), long-chain branching (LCB) and addition of particles to the polymer matrix on polymer melt properties were investigated using shear and extensional rheological techniques. The resulting structure-property relationships were established using newly introduced mechanical parameters under large amplitude oscillatory shear (LAOS) flow.

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49

Yang, Fang. "Deformation behaviour of beams reinforced with fibre reinforced polymer bars under bending and shear." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/7957/.

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Several predictive equations and design guidelines are currently available to estimate the total deformation of FRP reinforced concrete members. Although existing approaches can adequately estimate deflections up to service load, however, can also largely underestimate deflections at load levels beyond service. The larger-than expected deflections can be partly attributed to the stiffness degradation caused by the shear-flexure interaction and the change in the stiffness of the load carrying mechanisms. Although studies dealing with the shear behaviour of FRP reinforced concrete beams are currently available in the literature, these tend to focus primarily on the development of models to estimate ultimate shear strength rather than examine the effect of the FRP reinforcement on overall deformation behaviour. An experimental programme was designed to investigate the behaviour of FRP RC beams subjected to shear dominated actions, with a particular focus on their deformation behaviour. Six tests were carried out in two phases on three beams reinforced with FRP flexural and shear reinforcement. All specimens were tested in four point bending and two different shear span-to-depth ratios were examined, namely 3.5 and 2.8. Two different shear reinforcement ratios, 0.5% and 0.27%, were used to reinforce the two shear spans of each of the tested beams to examine the contribution of transverse reinforcement to the deformation behaviour. An analytical framework, based on a non-linear cross section analysis, was developed to perform load deformation analyses of RC beams. The framework was then extended to enable the use of different material models and to account for the effects of shear induced phenomena on overall deflections. On the basis of the results obtained from the experimental programme and the analytical framework, a new approach is proposed to model the development of a shear resisting truss mechanism and estimate the inclination of the compression struts. This concept is used to estimate shear induced deformation and improve existing models. Comparisons are carried out between the results provided by the analytical model and the experimental data, along with the load deflection responses estimated according to existing design guidelines and other models from current literature. This new model allows the inclusion of shear-induced deflection throughout the load history of the element and yields more accurate results.

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50

Ahlgren, Stephen G. "The Nucleation and Evolution of Riedel Shear Zones as Deformation Bands in Porous Sandstone." Thesis, The University of Arizona, 1999. http://hdl.handle.net/10150/249273.

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Riedel shear zones are geometric fault patterns commonly associated with strike-slip fault systems. The progressive evolution of natural Riedel shear zones within the Navajo Sandstone of southern Utah is interpreted from the spatial evolution of small-scale, incipient Proto-Riedel Zones (PRZs) to better-developed Riedel shear zones using field mapping and three-dimensional digital modeling. PRZs nucleate as a tabular zone of localized shearing marked by en èchelon deformation bands, each of which is no more than a few mm wide and tens of cm long, and oriented at 55° - 85° to the trend of the zone. With increasing strain, deformation bands and sedimentary markers are sheared ductily through granular flow and assume a sigmoidal form. The temporal and spatial evolution of bands comprising a Riedel shear zone suggests that PRZs nucleate as transitional-compactional deformation bands under localized, supra-lithostatic fluid pressure. Subsequent bands develop under modified regional stresses as conjugate shear fractures within the strain- hardened axis of the PRZ. These antithetic driven systems are not compatible with traditional synthetic driven models of Riedel shear zones. Unlike most synthetic driven examples, these antithetic driven systems are not controlled by preexisting "basement" structures, thus their geometries reflect a primary propagation or secondary passive deformation mechanism.

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Dissertations / Theses on the topic 'Shear deformation'

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