Effect of micro voids on stress triaxiality-plastic strain states of notched steels

Brittle fracture of structural steel for building use, in general, is triggered by a ductile crack initiated at notched surface after undergoing a noticeable amount of plastic strain. The initiation of the ductile crack correlates to the stress triaxiality-plastic strain states in the notched section. As stress triaxiality and plastic strain are usually derived from finite element analysis, two material models with voids (Gurson-Tvergaard-Needleman model) and without voids (Mises model) are used to do the analyses to study the stress triaxiality-plastic strain states in notched steels. The results show that the effect of micro voids on stress triaxiality-plastic strain states of notched steels is small until stability limit and become significant gradually after stability limit.