Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 21 for “"Slip System"”.
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The Role of Slip System Activation on Ni-Based Superalloy High Temperature Fatigue
… be caused by the activation of the {100} cubic slip plane along the usual {111} octahedral slip plane. This study continued the work of previous research by using SEM and EBSD imaging to characterize the microstructure of IN-718 specimens before and after preconditioning. The microstructure …
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Characterizing the southeast Caribbean-South American plate boundary at 64°W
… determine instead that the dextral strike-slip system along the Venezuelan coast cuts near-vertically through the crust and offsets the Moho. The strike-slip system fundamentally defines the plate boundary, deriving from a shear tear through the entire lithosphere that is actively …
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Single-crystal plasticity at finite strains: a computational investigation of hardening relations
… and implement a numerical algorithm to solve the system of equations that describe single-crystal viscoplasticity under finite strains. The second objective is to use the computer code that is developed to examine three hardening laws that have been proposed. The first is an isotropic hardening …
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Kinetics of Plastic Flow in Polycrystal Plasticity
… model. A modified power law is used to determine slip system activity without introducing artificial strain rate sensitivity. In addition, a slip system hardening law is introduced that is capable of modeling stage IV hardening. The evolution law uses two state variables and includes a hardening …
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The brittle and plastic response of quartz.
… quartz may not satisfy the Von Mises independent slip system criterion and clarification is required on the exact response to an imposed stress system at a given temperature.
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Deformation and residual stresses at the intragranular scale – a study using high energy x-ray diffraction and modeling in polycrystalline alloys
… residual stresses, stress triaxilities, slip system activities, strain rate sensitivities and intermittency in plasticity (jerky motion of dislocations) within individual grains of a Ti-7Al alloy sample so as to interpret the deformation mechanisms and locate any weak spots at that length …
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The origins of olivine fabric transitions and their effects on seismic anisotropy in the upper mantle
… by dislocation glide through the (010)[100] slip system. At higher strain rates evidence for the B-type fabric was observed, suggesting increased activity of the (010)[001] slip system at higher stresses. Recrystallization grains size and dislocation densities were used to estimate stresses …
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Plastic Deformation in Complex Crystal Structures
… low flow stresses, though on a limited number of slip systems: MAX phases, Mo$_2$BC, Nb$_2$Co$_7$ and Ta$_4$C$_{3-x}$ are examples of this. Where plastic flow is limited by the lattice resistance we must consider the effect of crystal structure on dislocation motion more directly. Aspects which …
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Experimental deformation of forsterite, wadsleyite and ringwoodite: Implications for seismic anisotropy of the Earth’s mantle
… and temperature is dominated by the [001]{hk0} slip system rather than the [100](010) glide which is extensively observed at low pressure and high temperature.. Concerning the high-pressure polymorphs, their plastic behaviour has been studied with a strong emphasis on the formation of CPO. …
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A microstructure based fatigue life prediction framework and its validation
… resolved shear stress, normal stress, slip-system length, and grain boundary character. In nickel-base superalloys, fatigue cracks tend to initiate near twin boundaries. The factors causing fatigue crack initiation depend on the material’s microstructure, the variability of which …
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Deformation Mechanisms at Grain Boundaries in Polycrystal Plasticity
… yield point, modeled using a formulation for slip system hardening that accounts for the evolution of mobile and forest dislocation densities---depicting boundary-dislocation and dislocation-dislocation interactions, respectively. In addition, the composite grain model is applied to predict …
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Strength and ductility of Mg alloys from first-principles
… 63 substitutional solutes on basal and prismatic slip in Mg. Using DFT and a flexible boundary condition method, we compute a-type basal and prismatic dislocation core structures and use these geometries to efficiently model the interaction of solutes with these cores based on solute interactions …
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Experimental constraints on the rheological behavior of olivine at upper mantle conditions
… have sought to understand the dynamic system driving the evolution of the earth, both at the surface and in the deep interior. While the deep earth contains far fewer phases than the crust, the inaccessibility of the mantle and core present a different challenge: unraveling the physical …
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Re-evaluating the tectonic model for the Arbuckle Mountains, Oklahoma by spatial and geometric analysis of stratigraphic and structural trends
… features indicate a large left lateral strike-slip system associated with the Washita Valley Fault. New interpretations indicate that this system hosts the Collings Ranch basin and that it’s bounding faults are not the same as previous interpretations.
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CONTINUUM DISLOCATION DYNAMICS MODELING OF THE DEFORMATION OF FCC SINGLE CRYSTALS
… are described by a set of vector fields, one per slip system, whose evolution is governed by curl-type kinetic equations describing the transport of dislocation lines. These kinetic equations are closed by specifying the velocity field in terms of a mobility law in which the driving force is …
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Low Energy Order-To-Disorder Transition Pathways In Phase-Change Nanowires
… recently shown that resistance switching in PCM systems such as superlattices and nanowires can occur at much lower current densities, where the temperature of the material always stays below its melting point. In-situ transmission electron microscopy (TEM) studies on nanowires, with a growth …
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The structural and engineering geology of the Country Rock at Finsch Mine
… was produced. The faulting belongs to a strike-slip system formed by crustal shear late during the Namaqua-Natal orogeny (ca. l.l Ga). A complex structural/tectonic history is suggested whereby transtension is followed by a rotation of the tectonic stress vectors with resultant transpression. …
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Micromechanical models of delamination in aluminum-lithium alloys
… of lattice deformation. The CP model implements slip system hardening with a modular approach to facilitate quick testing and calibration of different theories of hardening. The microscale models reveal soft/stiff grain boundaries develop elevated mean stress and plastic strain as a consequence …
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Fault Behavior and Kinematic Evolution of the Eastern California Shear Zone
… and near-field deformation of a fault system may be characterized to obtain an understanding of its kinematic evolution and potential seismic hazards. The dynamics and deformation history of the Eastern California shear zone (ECSZ), a wide and complex network of right-lateral …
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Mechanisms of deformation in beta-brass single crystals
… deformation, using optical microscopy to examine slip habits and transmission electron microscopy to examine dislocation substructures. Marked differences were observed in the stress/strain response, slip behaviour, and the substructural rearrangements of single crystals of β-brass when widely …
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