Abstract: new damage model and damage evolution equation for anisotropic ductile materials are established by introducing specific free energy and plastic potential with internal damage variable, of which the physical foundations are the principle of irreversible thermodynamics with internal variable, the minimum strength principle, the orthogonal flow rule and the effective stress proposed by Hill for anisotropic materials. The experimental data in the available literature are used to test the new damage evolution equation. It is found that this equation describes the damage evolution in anisotropic materials properly.

Key words: orthogonal anisotropic materials, damage mechanics, workability of metal forming process