Anisotropic Gurson‐Tvergaard‐Needleman plasticity and damage model for finite element analysis of elastic‐plastic problems

Abstract

Summary Implementation and analysis of the anisotropic version of the Gurson‐Tvergaard‐Needleman (GTN) isotropic damage criterion are performed on the basis of Hill's quadratic anisotropic yield theory with the definition of an effective anisotropic coefficient to represent the elastic‐plastic behavior of ductile metals. This study aims to analyze the extension of the GTN model suitable for anisotropic porous metals and to investigate the GTN model extension. An anisotropic damage model is implemented using the user material subroutine in ABAQUS/standard finite element code. The implementation is verified and applied to simulate a uniaxial tensile test on a commercially produced aluminum sheet material for three‐dimensional and plane stress test cases. Spherical and ellipsoidal micro voids are considered in the matrix material, and their effects on the uniaxial stress‐strain response of the material are analyzed. Hill's quadratic anisotropic yield theory predicts substantially large damage evolution and a low stress‐strain curve compared with those predicted by the isotropic model. An approximate model for anisotropic materials is proposed to avoid increased damage evolution. In this approximate model, Hill's anisotropic constants are replaced with an effective anisotropy coefficient. All model‐generated stress‐strain predictions are compared with the experimental stress‐strain curve of AA6016‐T4 alloy.

Ductile fracture modeling of metallic materials: a short review

“…These approaches, even if not representative of the true nature of an anisotropic damage variable, can be still useful in several engineering applications. In GTN-type models the anisotropic evolution of the void (and therefore of the damage) can be considered by adopting ad hoc laws with shape factors [124,125] that describes the volume and shape changes of the voids as well as their rotation during the loading process. The consideration of the void shape changes and reorientation complicates the formulation of group III models and their validation on three dimensional problems with complex loading conditions remains challenging.…”

Application of a GTN Damage Model Predicting the Fracture of 5052-O Aluminum Alloy High-Speed Electromagnetic Impaction

“…The sheet used in the simulation was made of 5052-O aluminum alloy. The constitutive behavior of the sheet is described by Equation (12) according to the fitting stress-strain curve ( Figure 12): σ = 377.23ε 0.25 (12) where σ is the true stress and ε is the true strain. The strain-rate sensitivity was ignored in the quasi-static deformation progress, whereas the quasi-static data were scaled to adapt to the high strain rate conditions in the high-speed electromagnetic forming using the Cowper-Symonds constitutive model.…”

Effect of Strain Rate Sensitivity on Fracture of Laminated Rings under Dynamic Compressive Loading

“…In this study, a numerical simulation of a fracture in a compressed ring is performed by an FE model in the commercial software ABAQUS. Some of the constitutive models to numerically evaluate large non-reversible deformation and fracture of ductile components under different loading situations are the Gurson-Tvergaard-Needleman (GTN), power law and Johnson-Cook (J-C) models [22][23][24]. In this work, because of the shear fracture mode in the compressed rings and considering the objectives to investigate the behavior of samples under different applied loads, the J-C model is utilized.…”