A new damage model for ductile materials

Abstract

In this paper, based on the irreversible thermodynamics and orthogonal flow rule, a microdamage evolution equation is first formulated, taking advantage of the specific free energy and plastic potential with internal variables. Furthermore, by analogy with the microdamage evolution equation, a macrodamage evolution equation is derived according to the principle of minimum strength. Afterwards, predictions are made for proportional loading and non-proportional loading, and the experimental data available in the relevant literature are used to verify these predictions. It can be concluded that the new damage model can successfully reveal the ductile damage evolution during the plastic deformation process. Thus, it opens the way to predict product quality and material workability for metal forming processes.