Cortain mechanical and physical approaches to analysis of macroplastic fracture criteria

A model of plastic fracture is developed as based on the concept of the supporting ability loss in the microvolume of the material. It considers a simultaneous growth and initiation of pores in the process of plastic deformation. The model permits predicting the effect of the variable rigidity of the stressed state, volume fraction of inclusions as well as their concentration and type on the value of critical deformation under plastic fracture. Effect of the stressed state rigidity on the critical deformation of materials where initiation of pores proceeds according to two different mechanisms is considered. It is shown that if mechanism of pores initiation is specified by a structure fragmentation and is typical of pure materials, the rigidity of stressed state affects a critical deformation less than in case of pore initiation on inclusions peculiar to the majority of structural materials. Linear damage summation rules are studied for their applicability to determine critical deformation of the material, the character of change in the stressed state rigidity in the process of deformation being different