Several physicomechanical approaches to the analysis of macroscopic failure. 2. Ductile failure

Abstract

1. The proposed model of ductile failure is based on the concept of a loss in the load bearing capability of a structural element of the material. It takes into consideration the simultaneous initiation and growth of the pores during plastic deformation. The model allows one to predict the effect of an alternating stress state rigidity, the volume fraction of inclusions, and also their concentration and type on the value of the critical strain during ductile failure. 2. It has been shown that the law of linear damage accumulation gives higher values of the critical strain if the stress state rigidity increases, and lower values if it decreases. The most reliable estimates using the linear damage accumulation law is observed with randomly alternating stress units. Nevertheless, in all of the investigated cases, the error in determining the critical strain ɛf using the linear law did not exceed 17%. In the case where ɛf is only determined by pore growth (nucleation of all of the pores occurs in the earliest stages of plastic deformation), the linear damage accumulation law is followed exactly. 3. Under a mechanism of pore growth caused by structural fragmentation and characteristic of clean materials, the stress state rigidity has less of an effect on the values of ɛf (especially at small values of the rigidity) then during pore nucleation on inclusions which is characteristic of structural materials.