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.

Advances in Virtual Metal Forming Including the Ductile Damage Occurrence: Application to 3D Sheet Metal Deep Drawing

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
K. Saanouni ◽  
H. Badreddine ◽  
M. Ajmal
Keyword(s):  
Sheet Metal ◽  
Constitutive Equations ◽  
Deep Drawing ◽  
Metal Forming ◽  
Ductile Damage ◽  
Classical Dynamic ◽  
Damage Initiation ◽  
Integration Schemes ◽  
Local Integration ◽  
Fully Coupled

An advanced numerical methodology to simulate virtually any sheet or bulk metal forming including various kinds of initial and induced anisotropies fully coupled to the isotropic ductile damage is presented. First, the fully coupled anisotropic constitutive equations in the framework of continuum damage mechanics under large plastic deformation are presented. Special care is paid to the strong coupling between the main mechanical fields such as elastoplasticity, mixed nonlinear isotropic and kinematic hardenings, ductile isotropic damage, and contact with friction in the framework of nonassociative and non-normal formulation. The associated numerical aspects concerning both the local integration of the coupled constitutive equations as well as the (global) equilibrium integration schemes are presented. The local integration is outlined, thanks to the Newton iterative scheme applied to a reduced system of ordinary differential equations. For the global resolution of the equilibrium problem, the classical dynamic explicit (DE) scheme with an adaptive time step control is used. This fully coupled procedure is implemented into the general purpose finite element code for metal forming simulation, namely, ABAQUS/EXPLICIT. This gives a powerful numerical tool for virtual optimization of metal forming processes before their physical realization. This optimization with respect to the ductile damage occurrence can be made either to avoid the damage occurrence to have a nondamaged part as in forging, stamping, deep drawing, etc., or to favor the damage initiation and growth for some metal cutting processes as in blanking, guillotining, or machining by chip formation. Two 3D examples concerning the sheet metal forming are given in order to show the capability of the proposed methodology to predict the damage initiation and growth during metal forming processes.

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.

Coupled Damage and Plasticity Modeling in Failure Analysis of Heated Concrete

2013 ◽  
Vol 671-674 ◽  
pp. 1531-1534
Author(s):  
Rong Tao Li
Keyword(s):  
Constitutive Model ◽  
Constitutive Equations ◽  
Iterative Procedure ◽  
Mechanical Analysis ◽  
Mapping Algorithm ◽  
Return Mapping ◽  
Return Mapping Algorithm ◽  
Damage Constitutive Model ◽  
Heated Concrete ◽  
Elastoplastic Damage

A coupled elastoplastic-damage constitutive model with consideration of chemo-induced material elastoplastic-damage effects due to heating concrete is proposed. A consistent return mapping algorithm for the integration of the rate coupled constitutive equations is developed. Consistent tangent modulus matrices for coupled chemo-thermo-hygro-mechanical analysis are derived to preserve the quadratic rate of convergence of the global Newton iterative procedure. Numerical results demonstrate the validity of the presented algorithm and illustrate the performance of the proposed constitutive model in reproducing coupled chemo-thermo-hygro-mechanical behavior in concretes subjected to fire.

Meshless Analyses of Fracture, Plasticity and Impact

2003 ◽  
Author(s):  
A. Eskandarian ◽  
Y. Chen ◽  
M. Oskard ◽  
J. D. Lee
Keyword(s):  
High Speed ◽  
Large Strain ◽  
Plastic Response ◽  
Governing Equations ◽  
Mapping Algorithm ◽  
High Speed Impact ◽  
Return Mapping ◽  
Return Mapping Algorithm ◽  
Large Strain Plasticity ◽  
Computational Plasticity

The governing equations for rate-independent large strain plasticity are formulated in the framework of meshless method. The numerical procedures, including return mapping algorithm, to obtain the solutions of boundary-value problems in computational plasticity are outlined. The crack growth process in elastic-plastic solid under plane strain conditions is analyzed. The large strain plastic response of material under high-speed impact is simulated. Numerical results are presented and discussed.

A coupled elastoplastic anisotropic damage model for rock materials

2020 ◽  
Vol 29 (8) ◽  
pp. 1222-1245
Author(s):  
Susheng Wang ◽  
Weiya Xu
Keyword(s):  
Coupling Effect ◽  
Damage Model ◽  
Coupled Model ◽  
Yield Function ◽  
Anisotropic Damage ◽  
Mapping Algorithm ◽  
Rock Materials ◽  
Return Mapping ◽  
Brittle Ductile Transition ◽  
Proposed Model

In this study, a rigorous constitutive model within the framework of thermodynamics is formulated to describe the coupling process between irreversible deformation and anisotropic damage of rock materials. The coupling effect is reflected based on the “two-surface” formulation. The plastic response is described by a yield function while the anisotropic damage is defined by a novel exponential damage criterion. In the proposed model, another feature lies in introducing parameters β and k in the proposed model to capture strain hardening/softening behaviors and brittle–ductile transition. The computational formulation scheme for the coupled model is deduced in detail by using return mapping algorithm. The validity of the coupled model is compared with the numerical simulation results and the experimental curves of the fine-grained sandstone, Beishan granite, and Jinping marble. The results indicate that the model can take into account the nonlinear mechanical behaviors of rock: coupling anisotropic damage and plasticity as well as brittle-ductile transition behaviors. Without loss of generality, the coupled model is versatile to describe the mechanical characteristics of rock materials.

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