The Evolution of Shear Bands in Sand: Numerical Investigations Based on an Elasto-Plastic Cosserat Continuum Approach

2014 ◽  
pp. 375-381
Author(s):  
B. Ebrahimian ◽  
M. I. Alsaleh
Keyword(s):  
Shear Bands ◽  
Cosserat Continuum ◽  
Continuum Approach ◽  
Numerical Investigations

Evolution of Shear Localization in an Elasto-Plastic Cosserat Material under Shearing

2013 ◽  
Vol 577-578 ◽  
pp. 21-24 ◽  
Author(s):  
Babak Ebrahimian
Keyword(s):  
Granular Layer ◽  
Shear Localization ◽  
Cosserat Continuum ◽  
Stationary Condition ◽  
State Variables ◽  
Particle Rotation ◽  
Continuum Approach ◽  
Shear Deformations ◽  
Numerical Investigations ◽  
Elasto Plasticity

Numerical investigations of shear localization evolution within a layer of granular material under large monotonic shearing are presented. Here, micro-polar (Cosserat) continuum approach is applied within the framework of elasto-plasticity to remove the numerical difficulties of localization modeling encountered in classical continuum. The micro-polar kinematical boundary conditions are used to model the rotation resistance of soil grains along the interface between granular layer and surface of adjoining structure. The finite element results show that shear localization takes place from the beginning of shearing and appears parallel to the direction of shearing, close to the boundary with less restriction of particle rotation. Furthermore, the state variables tend towards asymptotical stationary condition in large shear deformations.

Analysis of shear bands in slow granular flows using a frictional Cosserat model

2000 ◽  
Vol 627 ◽  
Author(s):  
Prabhu R. Nott ◽  
K. Kesava Rao ◽  
L. Srinivasa Mohan
Keyword(s):  
Scaling Laws ◽  
Shear Bands ◽  
Shear Layers ◽  
Theoretical Description ◽  
Field Variable ◽  
Cosserat Continuum ◽  
Momentum Balance ◽  
Rigid Plastic ◽  
Independent Field ◽  
Cosserat Model

ABSTRACTThe slow flow of granular materials is often marked by the existence of narrow shear layers, adjacent to large regions that suffer little or no deformation. This behaviour, in the regime where shear stress is generated primarily by the frictional interactions between grains, has so far eluded theoretical description. In this paper, we present a rigid-plastic frictional Cosserat model that captures thin shear layers by incorporating a microscopic length scale. We treat the granular medium as a Cosserat continuum, which allows the existence of localised couple stresses and, therefore, the possibility of an asymmetric stress tensor. In addition, the local rotation is an independent field variable and is not necessarily equal to the vorticity. The angular momentum balance, which is implicitly satisfied for a classical continuum, must now be solved in conjunction with the linear momentum balances. We extend the critical state model, used in soil plasticity, for a Cosserat continuum and obtain predictions for flow in plane and cylindrical Couette devices. The velocity profile predicted by our model is in qualitative agreement with available experimental data. In addition, our model can predict scaling laws for the shear layer thickness as a function of the Couette gap, which must be verified in future experiments. Most significantly, our model can determine the velocity field in viscometric flows, which classical plasticity-based model cannot.

Analysis of plane Couette shear test of granular media in a Cosserat continuum approach

2014 ◽  
Vol 69 (1) ◽  
pp. 106-115 ◽  
Author(s):  
Wenxiong Huang ◽  
Scott W. Sloan ◽  
Daichao Sheng
Keyword(s):  
Granular Media ◽  
Shear Test ◽  
Cosserat Continuum ◽  
Continuum Approach

Dynamic Patterning of Shear Bands in Cosserat Continuum

1997 ◽  
Vol 123 (2) ◽  
pp. 123-133 ◽  
Author(s):  
J. Tejchman ◽  
W. Wu
Keyword(s):  
Shear Bands ◽  
Cosserat Continuum

Numerical study on patterning of shear bands in a Cosserat continuum

1993 ◽  
Vol 99 (1-4) ◽  
pp. 61-74 ◽  
Author(s):  
J. Tejchman ◽  
W. Wu
Keyword(s):  
Numerical Study ◽  
Shear Bands ◽  
Cosserat Continuum
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