Damage Modeling in Metal Forming Processes

Fully coupled constitutive equations accounting for isotropic hardening as well as the ductile isotropic damage are implemented into the special purpose finite element code for metal forming simulation. First, the formulation of the fully coupled constitutive equations in the framework of the thermodynamics of irreversible processes with state variables is presented. The associated numerical aspects are then presented and discussed using the implicit integration schemes. The numerical implementation of the damage is made in such a manner that the calculations can be executed with or without damage effect, i.e., coupled or uncoupled calculations. Several numerical results are presented discussing the capability of the model to predict the damage initiation and growth during metal forming processes. For some geometrically simple examples, comparisons between coupled and uncoupled solutions are presented. The proposed methodology is then applied to numerically simulate various metal forming processes in order to predict the damage initiation.