An approximate lower bound damage-based yield criterion for porous ductile sheet metals

An approximate lower bound damage-based yield criterion is developed for isotropic porous ductile sheet metals. The matrix of the sheet metals is assumed to be elastic-perfectly plastic and obey the von Mises yield criterion with periodically distributed voids. Gurson’s unit-cell model is simplified to characterize the sheet metals. To accommodate biaxial loading, an approach of stress superposition is adopted for the stress analysis. Numerical results were calculated and compared to Gurson’s extended yield criterion and experimental results.