Abstract
This paper deals with the criterion and mechanical characteristics of the initial critical softening point of porous materials under different loading triaxiality. First, the concept of the initial critical softening point (hereafter abbreviated by ICSP) is defined. The close relations between the ICSP and other important phenomena, such as the failure initiation, void coalescence, localization, instability and ductile fracture in a porous material element are carefully annotated. Second, a criterion for predicting the ICSP is suggested and examined on the basis of a new rigid plastic constitutive model published previously. Third, the mechanical characteristics at or around the ICSP are systematically analyzed by numerical calculations. This research reveals the potentiality of applying the ICSP and corresponding criterion to control the fracture initiation and strength distribution in porous materials and prevent the materials from ductile fracture during plastic forming.
