IMPLICATIONS OF A CONSTITUTIVE MODEL FOR STRAIN LOCALIZATION

1988 ◽  
Vol 49 (C3) ◽  
pp. C3-489-C3-496
Author(s):  
B. D. COLEMAN ◽  
M. L. HODGDON
Keyword(s):  
Constitutive Model ◽  
Strain Localization

A Generalized Elasto-Plastic Micro-Polar Constitutive Model

2015 ◽  
Vol 798 ◽  
pp. 505-509 ◽  
Author(s):  
Lapo Gori ◽  
Roque Luiz da Silva Pitangueira ◽  
Samuel Silva Penna ◽  
Jamile Salim Fuina
Keyword(s):  
Structural Analysis ◽  
Constitutive Model ◽  
Numerical Method ◽  
Strain Localization ◽  
Continuum Model ◽  
Constitutive Models ◽  
Localization Problem ◽  
Polar Model ◽  
Basic Characteristics ◽  
Analysis Environment

This paper summarizes the implementation of an elasto-plastic constitutive model for a micro-polar continuum in the constitutive models framework of the software INSANE (INteractive Structural ANalysis Environment). Such an implementation is based on the tensorial format of a unified constitutive models formulation, that allows to implement different constitutive models independently on the peculiar numerical method adopted for the solution of the problem. The basic characteristics of the micro-polar continuum model and of the unified formulation of constitutive models are briefly recalled. A generalization of the micro-polar model is then introduced in order to include this model in the existent tensor-based formulation. Finally, an enhanced version of the general closest-point algorithm, ables to manage the generalized micro-polar formulation, is derived. A strain localization problem modeling illustrates the implementation.

scholarly journals Elastoplastic constitutive behavior and strain localization of a low-porosity sandstone during brittle fracturing

2021 ◽  
Author(s):  
Shihuai Zhang ◽  
Pei Guo ◽  
Shunchuan Wu
Keyword(s):  
Constitutive Model ◽  
Yield Surface ◽  
Strain Localization ◽  
Pure Shear ◽  
Failure Process ◽  
Frictional Coefficient ◽  
Peak Stress ◽  
Confining Pressure ◽  
Elastoplastic Behavior ◽  
Confining Pressures

We investigated the elastoplastic behavior and strain localization of the Zigong sandstone (porosity: 6.5%) during brittle fracturing based on two series of axisymmetric compression experiments. The experiments were conducted under various confining pressures (σ3 = 0 ~ 80 MPa). For each confining pressure, the sandstone specimens were deformed under constant axial and circumferential strain rates, respectively. When σ3 < 60 MPa, the sandstone first undergoes stable deformation in the post-peak stage and then loses its stability. Before the emergence of instability, the mechanical behavior is hardly affected by the controlling method. When the confining is larger, the sandstone manifests a stable failure process during the whole loading stage. The observed elastoplastic behavior was described by a two-yield surface constitutive model established in the framework of generalized plastic mechanics. The proposed constitutive model incorporates two quadratic yield functions, as well as two linearly independent plastic potential functions, to honor the shear yield and volumetric dilatancy, respectively. Via the return mapping algorithm, the proposed constitutive model was verified by comparing the numerical results with experimental results. In addition, the two-yield surface constitutive model, which is equivalent to the model proposed by Rudnicki and Rice,1 was applied to localization analysis. Assuming that the onset of localization occurs at peak stress, frictional coefficient μ and dilatancy factor β were determined from experimental data. The variations of both plastic parameters predict the transition of localization mode from pure dilation bands under uniaxial compression to pure shear bands at high confining pressures, which is consistent with the experimental observations.

Instability of an elasto-viscoplastic constitutive model for clay and strain localization

1994 ◽  
Vol 18 (2) ◽  
pp. 119-129 ◽  
Author(s):  
Fusao Oka ◽  
Toshihisa Adachi ◽  
Atsushi Yashima
Keyword(s):  
Constitutive Model ◽  
Strain Localization

An Analysis of Shear Localization During Bending of a Polycrystalline Sheet

1992 ◽  
Vol 59 (3) ◽  
pp. 491-496 ◽  
Author(s):  
R. Becker
Keyword(s):  
Plastic Deformation ◽  
Finite Element ◽  
Constitutive Model ◽  
Strain Localization ◽  
Texture Evolution ◽  
Rate Sensitivity ◽  
Shear Localization ◽  
Pure Bending ◽  
Stiffness Matrices ◽  
Localized Plastic Deformation

The development of shear localization in a polycrystalline sheet subject to pure bending is analyzed numerically using a slip-based constitutive model. The material response at each finite element integration point is determined by averaging the stiffness matrices from differently oriented FCC crystals. The effects of texture evolution, hardening, and strain-rate sensitivity are incorporated. The model predicts localized plastic deformation at both the tensile and the compressive surfaces of the sheet during bending. Comparison of the numerical results with a section of the bent sheet indicates that strain localization is predicted at the appropriate strain levels and orientations.

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