On mesh dependencies in finite-element-based damage prediction: application to sheet metal bending

The properties of a local and a regularised gradient-enhanced continuum damage model are highlighted and both types of models are applied to the simulation of an air bending process. Constitutive relations are summarised for both Lemaitre-type models and a brief description of their implementation into Abaqus user material subroutines is given. With (several) material parameters obtained from a basic parameter identification process, an air bending experiment is simulated with different mesh densities. By means of the damage evolution as well as the distribution of representative damage and hardening variables, the mesh dependence of the local model in contrast to the mesh independence of the gradient-enhanced model is analysed for two air bending processes with different die width.