A micromechanical model for ductile fracture prediction in ASTM A992 steels

• New micromechanics based ductile fracture initiation criterion for ASTM A992 structural steels is presented.
• Effect of important microscopic and macroscopic parameters on microvoid growth is studied for steel hardening matrix.
• Relative microvoid growth is considered as the damage indicator and its effect on relative microvoid growth is investigated.
• Micromechanics based fracture model is calibrated and validated for A992 steels.

This paper presents a new micromechanics based ductile fracture initiation criterion for ASTM A992 steels. The proposed criterion is developed using micromechanical study of microvoid growth using computational cell simulations. Parametric study is performed on cylindrical computational cells with an embedded spherical microvoid to describe the effects of stress state, matrix hardening properties and initial void volume fraction on microvoid growth. A micromechanical void growth model and a ductile fracture initiation criterion is proposed for ASTM A992 structural steels based on the parametric study. The model is calibrated and validated using experimental testing on eight notched ASTM A992 steel specimens. It is shown that the predicted ductile fracture initiation strains and fracture initiation locations from the proposed model matched fairly well with the experimental results.