scholarly journals An enhanced void-crack-based Rousselier damage model for ductile fracture with the XFEM

2018 ◽  
Vol 28 (6) ◽  
pp. 943-969 ◽  
Author(s):  
MIM Ahmad ◽  
JL Curiel-Sosa ◽  
S Arun ◽  
JA Rongong
Keyword(s):  
Ductile Fracture ◽  
Volume Fraction ◽  
Damage Model ◽  
Ductile Material ◽  
Integration Scheme ◽  
Extended Finite Element ◽  
Material Interfaces ◽  
Mapping Algorithm ◽  
Return Mapping ◽  
Return Mapping Algorithm

This work presents a modelling strategy for ductile fracture materials by implementing the Rousselier damage model with the extended finite element method (XFEM). The implicit integration scheme and consistent tangent modulus based on a radial return mapping algorithm for this constitutive model are developed by the user-defined material subroutine UMAT in ABAQUS/Standard. To enhance the modelling of the crack development in the materials, the XFEM is used that allows modelling of arbitrary discontinuities, where the mesh does not have to be aligned with the boundaries of material interfaces. This modelling strategy, so-called Rousselier-UMAT-XFEM (RuX) model, is proposed to connect both concepts, which gives an advantage in predicting the material behaviour of ductile material in terms of voids and crack relation. This is the first contribution where XFEM is used in ductile fracture analysis for micromechanical damage problems. The results indicate that the RuX model is a promising technique for predicting the void volume fraction damage and crack extension in ductile material, which shows a good agreement in terms of stress–strain and force–displacement relationships.

Two Efficient Algorithms of Plastic Integration for Sheet Forming Modeling

2007 ◽  
Vol 129 (4) ◽  
pp. 698-704 ◽  
Author(s):  
Y. M. Li ◽  
B. Abbès ◽  
Y. Q. Guo
Keyword(s):  
Equivalent Stress ◽  
Sheet Forming ◽  
Efficient Algorithms ◽  
Integration Scheme ◽  
Fast Method ◽  
Numerical Experience ◽  
Mapping Algorithm ◽  
Inverse Approach ◽  
Return Mapping ◽  
Return Mapping Algorithm

A fast method called the “inverse approach” for sheet forming modeling is based on the assumptions of the proportional loading and simplified tool actions. To improve the stress estimation, the pseudo-inverse approach was recently developed: some realistic intermediate configurations are geometrically determined to consider the deformation paths; two new efficient algorithms of plastic integration are proposed to consider the loading history. In the direct scalar algorithm (DSA), an elastic unloading-reloading factor γ is introduced to deal with the bending-unbending effects; the equation in unknown stress vectors is transformed into a scalar equation using the notion of the equivalent stress, thus the plastic multiplier Δλ can be directly obtained without iterative resolution scheme. In the γ-return mapping algorithm, the equivalent plastic strain increment estimated by DSA is taken as the initial solution in Simo’s return mapping algorithm, leading to a stable, efficient, and accurate plastic integration scheme. The numerical experience has shown that these two algorithms give a considerable reduction of CPU time in the plastic integration.

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.

Cyclic Loading of Beams Based on Kinematics Hardening Behavior Coupled With Isotropic Damage

2006 ◽  
Author(s):  
Ali Nayebi ◽  
Kourosh H. Shirazi
Keyword(s):  
Cyclic Loading ◽  
Strain Hardening ◽  
Kinematic Hardening ◽  
Damage Model ◽  
Mapping Algorithm ◽  
Return Mapping ◽  
Tension And Compression ◽  
Computational Aspects ◽  
Isotropic Damage ◽  
Path Dependent

The kinematic hardening theory of plasticity based on the Prager model and incremental isotropic damage is used to evaluate the cyclic loading behavior of a beam under the axial, bending, and thermal loads. This allows damage to be path-dependent. The damage and inelastic deformation are incorporated and they are used for the analysis of the beam. The beam material is assumed to follow linear strain hardening property coupled with isotropic damage. The material strain hardening curves in tension and compression are assumed to be both identical for the isotropic material. Computational aspects of rate independent model is discussed and the constitutive equation of the rate independent plasticity coupled with the damage model are decomposed into the elastic, plastic and damage parts. Return Mapping Algorithm method is used for the correction of the elastoplastic state and for the damage model the algorithm is used according to the governed damage constitutive relation. The effect of the damage phenomenon coupled with the elastoplastic kinematic hardening is studied for deformation and load control loadings.

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