Advanced Anisotropic Damage Model Fully Coupled with Anisotropic Plasticity

2015 ◽  
Vol 784 ◽  
pp. 153-160 ◽  
Author(s):  
Houssem Badreddine ◽  
Khemais Saanouni
Keyword(s):  
Finite Strain ◽  
Plastic Anisotropy ◽  
Consistency Condition ◽  
Yield Function ◽  
Loading Path ◽  
Large Strains ◽  
Anisotropic Damage ◽  
Anisotropic Plasticity ◽  
Plastic Potential ◽  
Fully Coupled

In this work, a thermodynamically-consistent framework is used to formulate a non-associative finite strain anisotropic elastoplastic model fully coupled with anisotropic ductile damage. The finite strain assumption is considered using specific large strains kinematics based on multiplicative decomposition of the total transformation gradient and assuming a small elastic strains. The objectivity principle fulfillment is assumed using the well-known rotating frame formulation. The effective variables are defined to introduce the effect of the anisotropic damage on the other variables through the total energy equivalence assumption. The non-associative plasticity framework, for which equivalent stresses in yield function and in plastic potential are separately defined, allows better plastic anisotropy description. The evolution equations for overall dissipative phenomena are deduced from the generalized normality rule applied to the plastic potential while the consistency condition is still applied to the yield function. Applications are made to an RVE with generic material parameters by considering non-proportional loading paths. For each loading path the effect of the anisotropic plasticity on the damage evolution is studied in the context of finite strains.

Effect of isotropic and anisotropic damage and plasticity on ductile crack initiation

2018 ◽  
Vol 28 (6) ◽  
pp. 918-942 ◽  
Author(s):  
Arash Keshavarz ◽  
Rahmatollah Ghajar
Keyword(s):  
Finite Element ◽  
Crack Initiation ◽  
Pipeline Steel ◽  
Plastic Anisotropy ◽  
Ductile Failure ◽  
Ductile Material ◽  
Anisotropic Damage ◽  
Plastic Behavior ◽  
Ductile Crack ◽  
Anisotropic Plasticity

In this article, the effects of plastic anisotropy and damage on ductile crack initiation (ductile failure) are studied in a thermodynamically consistent framework. First, isotropic and anisotropic continuum damage models of Lemaitre are modified to incorporate anisotropic plasticity. In the next stage, a subroutine is developed to add the damage formulation to Abaqus finite element package. A highly ductile material with anisotropic plastic behavior, API 5L X100 pipeline steel, is selected for this study. Finite element analyses are done to simulate isotropic/anisotropic plasticity coupled with isotropic/anisotropic damage. Finite element results are compared with the result of tests on smooth and notched specimens, and the effects of anisotropic plasticity, anisotropic damage, geometry changes, triaxiality in stress and their mutual effects and interactions on post yield behavior and crack initiation are studied.

scholarly journals An advanced elastoplastic framework accounting for induced plastic anisotropy fully coupled with ductile damage

2021 ◽  
pp. 106620
Author(s):  
J. Paux ◽  
M. Ben Bettaieb ◽  
H. Badreddine ◽  
F. Abed-Meraim ◽  
C. Labergere ◽  
...  
Keyword(s):  
Plastic Anisotropy ◽  
Ductile Damage ◽  
Fully Coupled

Failure Predictions for DP Steel Cross-die Test using Anisotropic Damage

2011 ◽  
Vol 21 (5) ◽  
pp. 713-754 ◽  
Author(s):  
M. S. Niazi ◽  
H. H. Wisselink ◽  
T. Meinders ◽  
J. Huétink
Keyword(s):  
Strain Rate ◽  
Damage Evolution ◽  
Damage Model ◽  
Anisotropic Damage ◽  
Continuum Damage ◽  
Anisotropic Plasticity ◽  
Continuum Damage Model ◽  
Damage Models ◽  
Isotropic Damage ◽  
Failure Predictions

The Lemaitre's continuum damage model is well known in the field of damage mechanics. The anisotropic damage model given by Lemaitre is relatively simple, applicable to nonproportional loads and uses only four damage parameters. The hypothesis of strain equivalence is used to map the effective stress to the nominal stress. Both the isotropic and anisotropic damage models from Lemaitre are implemented in an in-house implicit finite element code. The damage model is coupled with an elasto-plastic material model using anisotropic plasticity (Hill-48 yield criterion) and strain-rate dependent isotropic hardening. The Lemaitre continuum damage model is based on the small strain assumption; therefore, the model is implemented in an incremental co-rotational framework to make it applicable for large strains. The damage dissipation potential was slightly adapted to incorporate a different damage evolution behavior under compression and tension. A tensile test and a low-cycle fatigue test were used to determine the damage parameters. The damage evolution was modified to incorporate strain rate sensitivity by making two of the damage parameters a function of strain rate. The model is applied to predict failure in a cross-die deep drawing process, which is well known for having a wide variety of strains and strain path changes. The failure predictions obtained from the anisotropic damage models are in good agreement with the experimental results, whereas the predictions obtained from the isotropic damage model are slightly conservative. The anisotropic damage model predicts the crack direction more accurately compared to the predictions based on principal stress directions using the isotropic damage model. The set of damage parameters, determined in a uniaxial condition, gives a good failure prediction under other triaxiality conditions.

Effect of Material Frame Rotation on the Hardening of an Anisotropic Material in Simple Shear Tests

2018 ◽  
Vol 85 (12) ◽  
Author(s):  
Kelin Chen ◽  
Stelios Kyriakides ◽  
Martin Scales
Keyword(s):  
Simple Shear ◽  
Plastic Anisotropy ◽  
Yield Function ◽  
Strain Response ◽  
Shear Tests ◽  
Stress Strain ◽  
Anisotropic Yield Function ◽  
Torsion Experiment ◽  
Thin Walled Tube ◽  
Material Frame

The shear stress–strain response of an aluminum alloy is measured to a shear strain of the order of one using a pure torsion experiment on a thin-walled tube. The material exhibits plastic anisotropy that is established through a separate set of biaxial experiments on the same tube stock. The results are used to calibrate Hill's quadratic anisotropic yield function. It is shown that because in simple shear the material axes rotate during deformation, this anisotropy progressively reduces the material tangent modulus. A parametric study demonstrates that the stress–strain response extracted from a simple shear test can be influenced significantly by the anisotropy parameters. It is thus concluded that the material axes rotation inherent to simple shear tests must be included in the analysis of such experiments when the material exhibits anisotropy.

HERK integration of finite-strain fully anisotropic plasticity models

2021 ◽  
Vol 185 ◽  
pp. 103492
Author(s):  
P. Areias ◽  
T. Rabczuk ◽  
J. Ambrósio
Keyword(s):  
Finite Strain ◽  
Anisotropic Plasticity

scholarly journals Hierarchical creep cavity formation in an ultramylonite and implications for phase mixing

Solid Earth ◽  
2017 ◽  
Vol 8 (6) ◽  
pp. 1193-1209 ◽  
Author(s):  
James Gilgannon ◽  
Florian Fusseis ◽  
Luca Menegon ◽  
Klaus Regenauer-Lieb ◽  
Jim Buckman
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Finite Strain ◽  
Grain Boundary Sliding ◽  
Large Strains ◽  
Cavity Formation ◽  
Phase Mixing ◽  
Transient Phenomena ◽  
Boundary Sliding

Abstract. Establishing models for the formation of well-mixed polyphase domains in ultramylonites is difficult because the effects of large strains and thermo-hydro-chemo-mechanical feedbacks can obscure the transient phenomena that may be responsible for domain production. We use scanning electron microscopy and nanotomography to offer critical insights into how the microstructure of a highly deformed quartzo-feldspathic ultramylonite evolved. The dispersal of monomineralic quartz domains in the ultramylonite is interpreted to be the result of the emergence of synkinematic pores, called creep cavities. The cavities can be considered the product of two distinct mechanisms that formed hierarchically: Zener–Stroh cracking and viscous grain-boundary sliding. In initially thick and coherent quartz ribbons deforming by grain-size-insensitive creep, cavities were generated by the Zener–Stroh mechanism on grain boundaries aligned with the YZ plane of finite strain. The opening of creep cavities promoted the ingress of fluids to sites of low stress. The local addition of a fluid lowered the adhesion and cohesion of grain boundaries and promoted viscous grain-boundary sliding. With the increased contribution of viscous grain-boundary sliding, a second population of cavities formed to accommodate strain incompatibilities. Ultimately, the emergence of creep cavities is interpreted to be responsible for the transition of quartz domains from a grain-size-insensitive to a grain-size-sensitive rheology.

On the Modeling of Evolving Elastic and Plastic Anisotropy in the Finite Strain Regime – Application to Deep Drawing Processes

2012 ◽  
Vol 504-506 ◽  
pp. 679-684 ◽  
Author(s):  
Ivaylo N. Vladimirov ◽  
Michael P. Pietryga ◽  
Vivian Tini ◽  
Stefanie Reese
Keyword(s):  
Deep Drawing ◽  
Evolution Equations ◽  
Finite Strain ◽  
Kinematic Hardening ◽  
Plastic Anisotropy ◽  
Material Model ◽  
Internal Variables ◽  
Time Step ◽  
Finite Element Software ◽  
Structure Tensors

In this work, we discuss a finite strain material model for evolving elastic and plastic anisotropy combining nonlinear isotropic and kinematic hardening. The evolution of elastic anisotropy is described by representing the Helmholtz free energy as a function of a family of evolving structure tensors. In addition, plastic anisotropy is modelled via the dependence of the yield surface on the same family of structure tensors. Exploiting the dissipation inequality leads to the interesting result that all tensor-valued internal variables are symmetric. Thus, the integration of the evolution equations can be efficiently performed by means of an algorithm that automatically retains the symmetry of the internal variables in every time step. The material model has been implemented as a user material subroutine UMAT into the commercial finite element software ABAQUS/Standard and has been used for the simulation of the phenomenon of earing during cylindrical deep drawing.

On the Origin of Stiffening in Biopolymers

2005 ◽  
Vol 874 ◽  
Author(s):  
Erik Van der Giessen ◽  
Teun Koeman ◽  
Teun Van Dillen ◽  
Patrick Onck
Keyword(s):  
Network Model ◽  
Finite Strain ◽  
Strain Analysis ◽  
Large Strains ◽  
Minor Effect ◽  
Two Dimensional ◽  
Thermally Induced ◽  
Small Strains ◽  
Dimensional Network ◽  
A Minor

AbstractStrain stiffening of protein networks is explored by means of a finite strain analysis of a two-dimensional network model of cross-linked semiflexible filaments. The results show that stiffening is caused by non-affine network rearrangements that govern a transition from a bending dominated response at small strains to a stretching dominated response at large strains. Thermally-induced filament undulations only have a minor effect; they merely postpone the transition.

Sign in / Sign up

Export Citation Format

Share Document