Effect and fracture analysis of inertia on dynamic void growth process of ductile metals

The Gurson model is achieved by UMAT (user defined material subroutine) and VUMAT (vectorized user defined material subroutine) subroutines, which are the interfaces provided by Abaqus software, respectively. UMAT is used for standard calculation module in Abaqus software, ignoring inertial effect, while VUMAT for Explicit calculation module in Abaqus software, containing inertial effect. After the calculated results are analyzed comparatively, the influence of inertial effect on void growth behavior is investigated. The results show that: (1) Inertial effect is sensitive to loading rate, with the increasing of the loading rate, inertial effect restrains void growth in the beginning, then it accelerates void growth; (2) There is a critical loading rate, at which inertial effect has no influence on void growth, for aluminum alloy LY12CZ, the critical loading rate is about 1740 s^-1; (3) From the view of inertial effect, it can explain the phenomena that the fracture strain increases along with the increasing of strain rate at dynamic loading condition. Besides, it also can explain the characteristic of 'brittleness' performed by aluminum alloys at higher loading condition.