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Showing 1 to 20 of 44 for “"Shear Bands"”.
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Dynamic Shear Bands in Metals under High Strain Rates
Adiabatic shear bands have been observed for a long time to occur under different conditions in many applications. Analysis of these localizations highly depends on the selection of the constitutive model. Hence, two constitutive models that take temperature and strain rate effect into account are …
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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 Simulation of Adiabatic Shear Bands and Crack Propagation in Thermoviscoplastic Materials
… The formation and propagation of an adiabatic shear band (ASB) inplane strain tensile deformations is studied for eleven materials. The ASB is assumed to form when the maximum shear stress has been reduced to 80% of its peak value at a point and it is deforming plastically. The materials are …
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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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Deformation Localization in Constrained Layers of Metallic Glasses: A Parametric Modeling Analysis
Localized plastic deformation known as shear banding is a prominent feature in metallic glasses. In this study we perform parametric three-dimensional finite ele- ment analyses, using primarily a thin layer of metallic glass on top of a cylindrical base, to study how physical constraint can affect …
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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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Finite Element Modeling of Strain Localization Initiated by Geometric Irregularities
… into zones of intense straining, known as shear bands, is a common phenomenon in inelastic deformation. The modeling of this phenomenon by the finite element method is hampered by a number of factors; the lack of a priori knowledge of the location, direction, and onset of the localized …
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Analyzing internal shearing in compound landslides using MPM
… In addition to the resistance offered by basal shear surfaces, internal shearing also influences the stability and kinematics of compound landslides. For compound landslides, internal shearing is essential to develop feasible sliding mechanisms. The internal distortion is caused by the formation …
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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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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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Constitutive Behavior of Bulk Metallic Glass Composites at Ambient and High Temperatures
… catastrophically via one dominant or multiple shear bands. These limitations can be overcome by producing BMG composites, which contain crystalline phases, resulting in an increase in ductility and reduction of catastrophic failure. BMG composites fall into two categories: intrinsic (in-situ) …
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The strain rate dependent mechanical properties and modelling of bovine cortical bone in compression
… of bovine bone leads to the formation of shear bands and that fracture depends on the orientation of the vascular porosity.
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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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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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Development of an efficient finite volume computational platform for the simulation of complex flows of complex fluids governed by the Rolie-Poly model
… flows but are not able to do so in some cases, shear-banding phenomena being one of them. Under certain flow conditions, some complex fluids have been shown to exhibit different shear bands in the flow field due to flow-induced material non-homogeneities. It is becoming increasingly clear that …
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Computational analysis of non-isothermal flow of non-Newtonian fluids
… such as the emergence of regions of different shear rates (shear bands) within the flow field. It has also been observed that the reacting mixture in reaction injection molding of polymeric foams undergoes self-expansion with evolution of heat due to exothermic chemical reaction. These …
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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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Mathematical Analysis on the PEC model for Thixotropic Fluids
… is analyzed. We model the flow when simple shearing is imposed by prescribing a total stress. One part of this dissertation focuses on oscillatory shear stresses. In shear flow, different fluid states corresponding to yielded and unyielded phases occur. We use asymptotic analysis to study …
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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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