Prediction of DP steel fracture by FEM simulationsusing an advanced Gurson model

• Main Author: Fansi, Joseph
• Language: ENG
• Published: 2013
• Subjects: [SPI:OTHER] Engineering Sciences/Other; [SPI:OTHER] Sciences de l'ingénieur/Autre; Formability; Gurson model; Plasticity anisotropy; Finite element; Sheet flange damages; Fracture initiation
• Online Access: http://pastel.archives-ouvertes.fr/pastel-00944529; http://pastel.archives-ouvertes.fr/docs/00/94/45/29/PDF/FANSI.pdf

This numerical investigation of an advanced Gurson-Tvergaard-Needleman (GTN) model is an extension of the original work of Ben Bettaieb et al. (2011). The model has been implemented as a user-defined material model subroutine (VUMAT) in the Abaqus/explicit FE code. The current damage model extends the previous version by integrating the three damage mechanisms: nucleation, growth and coalescence of voids. Physically based void nucleation and growth laws are considered, including an effect of the kinematic hardening. These new contributions are based and validated on experimental results provided by high-resolution X-ray absorption tomography measurements. Also, the numerical implementation of the kinematic hardening in this damage extension has obliged to readapt the classical triaxiality definition. Besides, a secondary fracture initiation criterion based on the ultimate average inter-cavities distance has been integrated to localize and quantify with good accuracy the strain distribution just before the material fails apart. The current damage model is applied in industrial conditions to predict the damage evolution, the stress state and the fracture initiation in various tensile thin flat sheet geometries and the cross-die drawing tests.