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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 37 for “"Shear Band"”.
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Shear-band structure in metallic glasses
… structural materials), strain localization into shear bands make these defects play a decisive role in controlling the plastic behavior of MGs. However, the characterization of shear bands has not yet succeeded in connecting their structural evolution and damage accumulation with any macroscopic …
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Finite element analysis of shear band failure with particular reference to circular plate impact
… the problem of the numerical simulation of the shear band or 'plugging' mode of failure in metallic solids. Particular reference is made to the normal impact between blunt projectiles and circular plates of thin to intermediate thickness. The thesis presents a two dimensional axisymmetric and …
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The mechanics of shear-band formation in thermal viscoplastic materials at high rates of loading
The mechanics of adiabatic shear bands are investigated through the study of a one-dimensional simple shearing model. The materials considered are assumed to exhibit strain rate hardening, thermal softening, and strain hardening or softening. The mechanism leading to shear band formation is assumed …
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Development of a New Ring Shear Apparatus for Investigating the Critical State of Sands
The present study investigates the shearing behavior of sands pertinent to liquefaction and critical state soil mechanics using an improved ring shear apparatus designed and constructed at the University of Illinois. Undrained/constant volume and drained triaxial compression and ring shear tests …
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Effect of Material and Geometric Parameters on Deformations of a Dynamically loaded Prenotched Plate
… stress and the initiation and propagation of shear bands at the notch-tip is analyzed. It is found that for high impact speeds or enhanced thermal softening, two shear bands, one at and the other at to it propagate from the notch tip. Otherwise, only one shear band nearly parallel to the …
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Analysis of Adiabatic Shear Banding in a Thick-Walled Steel Tube by the Finite Element Method
The initiation and propagation of adiabatic shear bands is analyzed numerically for an impulsively loaded thick-walled steel tube. A circumferential V-notch located at the outer surface of the center of the tube provides a stress concentration. The material is modeled as strain hardening, …
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Analysis of the Stability and Response of Deep-Seated Landslides by Monitoring their Basal Temperature
… minerals. This kind of landslides geometrically shears as translational/rotational (depending on the stratigraphy of the area), with very low velocities (cm/year) during long periods (years to tens of years). However, their collapse is usually very sudden, happening within minutes and without …
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Finite Element Analysis of Adiabatic Shear Bands in Impact and Penetration Problems
… of this work is to ascertain when and where a shear band, defined as a narrow region of rapid, intense plastic deformation, forms in each material subject to impact loading. The Taylor impact simulations show that shear bands form earlier in WHA than in DU for the material parameters used. In …
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Numerical modeling of strain localization in granular materials using Cosserat theory enhanced with microfabric properties
… investigate the strain localization phenomenon "shear bands" in granular materials. The micro-polar theory was used as the mathematical foundation for the continuum formulations. A laboratory testing results are used for verification and comparison with the numerical simulation. Silica sand and …
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Nanomechanical studies of metallic glasses at ambient and elevated temperatures
… including quasi-brittle failure along shear bands, extremely limited tensile ductility, and propensity for fatigue under cyclic loading. Though researchers have studied metallic glasses for the last fifty years, several fundamental aspects of the mechanical deformation process in these …
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Investigation of Parameters Influencing Reverse Fault Rupture Propagation to the Ground Surface
… Relatively large dimensions were chosen so that shear wave velocity measurements could be taken directly without interference from the walls of the apparatus. Experiments were conducted on loose sand, dense sand, stiff clay, and soft clay. The same sand was used for both the dense and loose sand …
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Understanding self-assembly and flow heterogeneities in poloxamer wormlike micelles
… nonlinear flow behavior such as the formation of shear bands and other flow heterogeneities, which have garnered considerable scientific interest. While often formulated using small molecule ionic surfactants, WLMs can also form in solutions of amphiphilic block polymers. The most well-studied of …
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Constitutive Modelling of Shear Localisation in Saturated Dilative Sand
… hydraulic gradient drives fluid into dilating shear zones. It loosens the soil and diminishes the shear strength. Continuum-based finite element method cannot apprehend pore-fluid movements at grain scale without extreme mesh refinement. This thesis aims to evaluate the capabilities of the …
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A continuum constitutive model for amorphous metallic materials
… depth curves, and the evolution of corresponding shear-band patterns under the in-denter. The numerical simulations are shown to compare very favorably with the corresponding experimental results. The constitutive model is subsequently extended to the high homologous temperature regime, and the …
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Kinetics of Plastic Flow in Polycrystal Plasticity
… the transition from continuous to discontinuous shear band propagation as the applied strain rate is decreased. Across this transition the stress drop magnitude and duration distributions are characterized by a shift away from power law relations towards peaked distributions. These shifts are …
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Localization and instability in sheared granular materials: role of friction and vibration
Shear banding and stick-slip instabilities have been long observed in sheared granular materials. Yet, their microscopic underpinnings, interdependencies and variability under different loading conditions have not been fully explored. Here, we use a non-equilibrium thermodynamics model, the Shear …
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THE YIELDING TRANSITION IN SOFT AMORPHOUS SOLIDS UNDER OSCILLATORY SHEAR: FROM MICROSCOPIC REARRANGEMENTS TO MACROSCOPIC FAILURE
… in amorphous solids. By exploiting a custom shear-cell coupled to a standard bright-field microscope, we provide a unique multiscale analysis of the yielding transition under oscillatory shear overcoming the limitation of conventional rheological measurements. Through a novel acquisition …
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INVESTIGATING THE IMPACT OF ROCK BRIDGES ON THE MECHANICAL BEHAVIOR OF JOINTED ROCK MASS USING LATTICE SPRING-BASED SYNTHETIC ROCK MASS (LS-SRM) APPROACH
… Surface Methodology (RSM). The results of direct shear models reveal that the LS-SRM method effectively replicates the failure mechanisms and peak shear strength of pre-existing rough two flows rock-like specimens with coplanar and non-coplanar rock bridges. As the normal stress levels increased, …
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