Extended mean-field method for predicting yield behaviors of porous materials

We extend Qiu and Weng's mean-field approach for predicting yield behaviors of porous metals [J. Appl. Mech.-Trans. ASME 59, 261-268, 1992] in a more rigorous mathematical form. This extended method can explicitly take account of the pore morphology and the elastic and plastic anisotropies of metal matrix. The validity of our method is first demonstrated by applying to the lotus-type porous iron that exhibits the anisotropic yield behavior experimentally. We next consider the porous materials possessing elastically and plastically anisotropies, and carry out the calculations of their macroscopic yield behaviors. The calculations revealed that the yield stress is virtually independent of the elastic anisotropy of the matrix, but strongly depends on the plastic anisotropy and also on the pore morphology.