Anisotropic ductile damage fully coupled with anisotropic plastic flow: Modeling, experimental validation, and application to metal forming simulation

2014 ◽  
Vol 23 (8) ◽  
pp. 1211-1256 ◽  
Author(s):  
W Rajhi ◽  
K Saanouni ◽  
H Sidhom
Keyword(s):  
Plastic Flow ◽  
Metal Forming ◽  
Kinematic Hardening ◽  
Ductile Damage ◽  
Damage Effect ◽  
Anisotropic Damage ◽  
State Variables ◽  
Energy Equivalence ◽  
Anisotropic Plastic ◽  
Equivalence Assumption

The main goal of this paper is the modeling, numerical simulation, and experimental validation of the anisotropic ductile damage effects on initially anisotropic plastic flow with mixed (isotropic and kinematic) nonlinear hardening under large plastic strains for metal forming processes simulation. A symmetric second-rank damage tensor together with a symmetrized fourth-rank damage-effect tensor is used to describe the anisotropic ductile damage evolution and its effect on the large plastic flow with hardening. Following the concept of effective state variables in the framework of the total energy equivalence assumption, the “Murakami” fourth-rank damage-effect tensor is chosen to describe the anisotropic damage effect on the elastic-plastic behavior including the mixed hardening. The “Lemaitre” ductile anisotropic damage evolution relationships, where the principal directions of the damage rate tensor are governed by those of the plastic strain rate tensor, are used. As difference with the works cited above, the nonlinear mixed isotropic and kinematic hardening is taken into account considering the full and strong damage effects through the effective state variables deduced from the total energy equivalence assumption initially proposed by Saanouni et al. The non-associative plasticity theory is considered, and the “ Hill 1948 ” quadratic (equivalent) stress norm is used to describe the large plastic anisotropic flow accounting for mixed isotropic and kinematic hardening with anisotropic damage effects. The formulation is performed assuming finite plastic strains and small elastic strains through the so-called rotated frame formulation. The obtained model was implemented into ABAQUS/Explicit® FE software thanks to the user’s developed subroutine VUMAT. The numerical aspects related to the time discretization of the fully coupled anisotropic constitutive equations are carefully described. Finally and for the validation purpose, the model is identified using an appropriate experimental data base concerning the grade 316L stainless steel to simulate numerically some metal forming processes.

An Anisotropic Damage Model for Ductile Metals

2002 ◽  
Author(s):  
Youssef Hammi ◽  
Mark F. Horstemeyer ◽  
Doug J. Bammann
Keyword(s):  
Damage Model ◽  
Ductile Damage ◽  
Damage Effect ◽  
Irreversible Processes ◽  
Plastic Strain Rate ◽  
Fracture Mechanisms ◽  
Anisotropic Damage ◽  
Strain Rate Tensor ◽  
State Variables ◽  
Rate Dependent

An anisotropic ductile damage description is motivated from fracture mechanisms and physical observations in Al-Si-Mg aluminum alloys with second phases. Ductile damage is induced by the classical process of nucleation of voids at inclusions, followed by their growth and coalescence. These mechanisms are related to different microstructural and length scale parameters like the fracture toughness, the void size, the intervoid ligament distance, etc. The classical thermodynamic constraints of irreversible processes with material state variables are used to model the tensorial damage evolution coupled to the Bammann-Chiesa-Johnson (BCJ) rate-dependent plasticity. The damage-plasticity coupling is based on the effective stress concept, assuming the total energy equivalence, and written through a deviatoric damage effect tensor on the deviatoric part and through the trace of the second rank damage tensor on the hydrostatic part. The damage rate tensor is additively decomposed into a nucleation rate tensor, a void growth rate scalar, and a coalescence rate tensor. The induced damage anisotropy is mainly driven by the nucleation, which evolves as a function of the absolute value of the plastic strain rate tensor. Finally, some experimental data of cast A356 aluminum alloy are correlated with predictive void-crack evolution to illustrate the applicability of the anisotropic damage model.

Application of an efficient anisotropic damage model to the prediction of the failure of metal forming processes

2019 ◽  
Vol 28 (10) ◽  
pp. 1556-1579 ◽  
Author(s):  
Ali Salehi Nasab ◽  
Mohammad Mashayekhi
Keyword(s):  
Constitutive Equations ◽  
Metal Forming ◽  
Kinematic Hardening ◽  
Ductile Damage ◽  
Irreversible Processes ◽  
Anisotropic Damage ◽  
Mapping Algorithm ◽  
Return Mapping ◽  
Integration Schemes ◽  
Return Mapping Algorithm

The main objective of this study is the numerical implementation of an advanced elastic–plastic model fully coupled with anisotropic ductile damage. The implemented formulation has been defined in the framework of thermodynamics of irreversible processes and a symmetric second-order tensor is adopted to describe the anisotropic damage state variable. After a summary of the main constitutive equations is given, the numerical integration of constitutive equations is performed using implicit and asymptotic integration schemes. Finite element simulation is performed using ABAQUS/Explicit software and the developed VUMAT subroutine. Next, the application of the developed model to T-shaped hydroforming of tubes and square-cup deep drawing metal forming processes is thoroughly discussed and failure onset zones due to anisotropic ductile damage growth are predicted and the results were consistent with the literature. Finally, by making an assumption that kinematic hardening can be ignored, an elastic predictor/plastic corrector algorithm requiring the solution of one equation is introduced. The assessment of the developed one-equation return-mapping algorithm is carried out by applying it to the simulation of the tensile test of a pre-notched bar. The Central Prossessing Unit time decreases noticeably using one-equation return mapping algorithm compared to the conventional return mapping algorithm and the numerical results are in good agreement with previous numerical simulations and experiments.

A Generalized Mixed Kinematic-Isotropic Hardening Plastic Model Coupled With Anisotropic Damage for Sheet Metal Forming

2002 ◽  
Author(s):  
C. L. Chow ◽  
X. J. Yang
Keyword(s):  
Sheet Metal ◽  
Sheet Metal Forming ◽  
Metal Forming ◽  
Kinematic Hardening ◽  
Isotropic Hardening ◽  
Strain History ◽  
Anisotropic Damage ◽  
Plastic Model ◽  
Localized Necking ◽  
Element Simulation

The paper presents a generalized mixed isotropic-kinematic hardening plastic model coupled with anisotropic damage for sheet metal forming. A nonlinear anisotropic kinematic hardening is developed. For the predication of limit strains at localized necking in stamping under complex strain history, the model and its associated damage criterion for localized necking are established and implemented into LS-DYNA3D by compiling it as a user subroutine. The finite element simulation of LS-DYNA3D based on the present model is carried out. The location of localized necking for sheet metal forming has been successfully identified.

Effect of Anisotropic Plastic Flow on the Ductile Damage Evolution in Hydrobulging Test of Thin Sheet Metal

2005 ◽  
Vol 8 (2-3) ◽  
pp. 271-289 ◽  
Author(s):  
Morad Khelifa ◽  
Houssem Badreddine ◽  
Abdelaziz Daoud ◽  
Mohamed Amen Gahbiche ◽  
Khémaïs Saaouni ◽  
...  
Keyword(s):  
Sheet Metal ◽  
Plastic Flow ◽  
Damage Evolution ◽  
Thin Sheet ◽  
Ductile Damage ◽  
Thin Sheet Metal ◽  
Anisotropic Plastic

Non-Associative Finite Strain Plasticity Coupled With Anisotropic Ductile Damage for Metal Forming

2012 ◽  
Author(s):  
T. Dung Nguyen ◽  
Houssem Badreddine ◽  
Khémais Saanouni
Keyword(s):  
Strong Coupling ◽  
Constitutive Equations ◽  
Damage Mechanics ◽  
Yield Criterion ◽  
Plastic Anisotropy ◽  
Continuum Damage Mechanics ◽  
Ductile Damage ◽  
Damage Effect ◽  
Irreversible Processes ◽  
State Variables

This paper presents the formulation of an advanced mechanical model describing a wide class of anisotropic elastoplastic constitutive equations accounting for the strong coupling with the anisotropic ductile damage. This model is developed within the framework of thermodynamics of irreversible processes with state variables and the continuum damage mechanics. The plastic anisotropy is accounted for through a non-associative theory for which a plasticity yield criterion and the plastic potential are defined separately but considering the strong coupling between both phenomena. The damage anisotropy is defined by using a second rank tensor. The effect of damage on the mechanical fields (stress, hardening, plastic strain, etc…) is described by a fourth rank damage effect operator that is defined in the context of the hypothesis of total energy equivalence. A rotating frame formulation is used to fulfil the objectivity of the constitutive equations under finite transformation. Finally, in order to illustrate the predictive capabilities of the model, the parametric studies with some simple loading case are investigated and the results discussed on the light of the anisotropic character of the ductile damage and its interaction with the anisotropy of plastic flow.

Modeling of Anisotropic Damage for Ductile Materials in Metal Forming Processes

2002 ◽  
Author(s):  
Youssef Hammi ◽  
Mark F. Horstemeyer ◽  
Doug J. Bammann
Keyword(s):  
Metal Forming ◽  
Ductile Damage ◽  
Fracture Mechanisms ◽  
Anisotropic Damage ◽  
Ductile Metals ◽  
Explicit Finite Element ◽  
Microstructural Parameters ◽  
Fully Implicit ◽  
Rate Dependent ◽  
Second Phases

The primary goal of this study is to model the anisotropic effect of ductile damage in metal forming processes. To represent the ductile metals, an anisotropic ductile plasticity/damage formulation is considered within the framework of continuum mechanics. The formulation is motivated from fracture mechanisms and physical observations in Al-Si-Mg aluminum alloys with second phases. The ductile damage mechanisms are represented by the classical ductile process of nucleation of voids at inclusions, followed by their growth and coalescence. Functions of each mechanism evolution are related to different microstructural parameters. The damage, represented by a second rank tensor, is coupled to the Bammann-Chiesa-Johnson (BCJ) rate-dependent plasticity using the effective stress concept. The constitutive equations are integrated using a fully implicit scheme and implemented into a explicit finite element code. This implementation is used to predict damage during the forward axisymmetric extrusion of an aluminum bar. This example illustrates the applicability of the model to predict the initiation and the evolution of anisotropic damage in metal forming processes.

Advanced Numerical Simulation of Metal Forming Processes Using Adaptive Remeshing Procedure

2009 ◽  
Vol 614 ◽  
pp. 27-33 ◽  
Author(s):  
Abel Cherouat ◽  
Laurence Giraud-Moreau ◽  
Houman Borouchaki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Metal Forming ◽  
Kinematic Hardening ◽  
Ductile Damage ◽  
Element Analysis ◽  
Strongly Coupled ◽  
Damage Initiation ◽  
Explicit Solver ◽  
Automatic Mesh

This paper presents an advanced numerical methodology which aims to improve virtually any metal forming processes. It is based on elastoplastic constitutive equations accounting for non-linear mixed isotropic and kinematic hardening “strongly” coupled with isotropic ductile damage. During simulation of metal forming processes, where large plastic deformations with ductile damage occur, severe mesh distorsion takes place after a finite number of incremental steps. Hence an automatic mesh generation with remeshing capabilities is essential to carry out the finite element analysis. Besides, when damage is taken into account a kill element procedure is needed to eliminate the fully damaged elements in order to simulate the growth of macroscopic cracks. The necessary steps to remesh a damaged structure in finite element simulation of forming processes including damage occurrence (initiation and growth) are given. An important part of this procedure is constituted by geometrical and physical error estimates. The meshing and remeshing procedures are automatic and are implemented in a computational finite element analysis package (ABAQUS/Explicit solver using the Vumat user subroutine). Some numerical results are presented to show the capability of the proposed procedure to predict the damage initiation and growth during the metal forming processes.

New Tensors for Anisotropic Damage in Continuum Damage Mechanics

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
George Z. Voyiadjis ◽  
Mohammed A. Yousef ◽  
Peter I. Kattan
Keyword(s):  
Mechanical Behavior ◽  
Elastic Energy ◽  
Elastic Strain ◽  
Damage Mechanics ◽  
Continuum Damage Mechanics ◽  
Damage Effect ◽  
Anisotropic Damage ◽  
Continuum Damage ◽  
Energy Equivalence ◽  
Scalar Invariant

In this work, new proposed damage tensors are studied in order to investigate the damage effect variables in the mechanical behavior of materials. All cases studied in this work are defined in terms of the elasticity of the material and based on the hypotheses of both elastic strain equivalence and elastic energy equivalence. Moreover, the new proposed damage tensors are anisotropically expressed in terms of the well-known damage effect tensor M. The principal-valued damage effect tensor is used to obtain the first scalar invariant of that tensor and its inverse, which are employed in expressing and verifying the new proposed damage tensors. The study demonstrates that most of the new proposed damage tensors are verified within the framework of continuum damage mechanics. In addition, new hybrid damage tensors are proposed which are defined in terms of the damage effect tensor and the new proposed damage tensors. The new hybrid damage tensors are eventually expressed in terms of the damage effect tensor.

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