ELASTIC-PLASTIC CRACK ADVANCE UNDER STEADY-STATE ACCOMPANIED BY THE MICRO-VOID GROWTH
伴随微孔洞生长的裂纹弹塑性定常扩展

When a crack propagates along the ductile material, a process of the void nucleation and growth will be accompanied. The global fracture toughness and strength of material will be influenced considerably due to void nucleation and evolution. Previous researches have mainly focused on the fracture process, in which crack advance is described by a process of the void nucleation, growth and coalescence. In this paper, based on the conventional fracture process zone models, the effects of micro-void nucleation and growth on the global fracture toughness are studied. In the research, a set of the increment constitutive equations of plasticity is derived based on the Gurson's model, and then used to the steady-state crack advance case directly. The effect of voids on the fracture toughness is described by the constitutive equations. The approach is different from that by adopting the void coalescence model, the effect is mainly expressed with the change of the fracture process zone. The results of present research show that the global fracture toughness of material will decrease with void nucleating and growing, and as the initial void volume fraction increases,crack propagates with brittle characteristics and material is in the void damage failure.