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Gradient plasticity modelling of strain localization in granular materials
Author(s) -
Al Hattamleh O.,
Muhunthan B.,
Zbib H. M.
Publication year - 2004
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/nag.345
Subject(s) - materials science , plasticity , constitutive equation , softening , mechanics , shear band , finite element method , displacement (psychology) , granular material , stress (linguistics) , deformation (meteorology) , shear stress , velocity gradient , composite material , shear (geology) , physics , thermodynamics , psychology , linguistics , philosophy , psychotherapist
The flow stress in the yield surface of plastic constitutive equation is modified with a higher order gradient term of the effective plastic strain to model the effect of inhomogeneous deformation in granular materials. The gradient constitutive model has been incorporated into the finite element code ABAQUS and used to simulate biaxial shear tests on dry sand. It is shown that the shape of the post‐peak segment of the load displacement curve predicted by the numerical analysis is dependent on the mesh size when gradient term is not used. Use of an appropriate gradient coefficient is shown to correct this and predict a unique shape of the load displacement curve regardless of the mesh size. The gradient coefficient required turns out to be approximately inversely proportional to the mesh elemental area. Use of the strain gradient term is found to diffuse the concentration of plastic strains within shear band resulting in its consistent width. The coefficient of the higher gradient term appears as a function of the grain size, the mean confining stress, and the plastic softening modulus. Copyright © 2004 John Wiley & Sons, Ltd.