Finite element simulations of the high velocity expansion and fragmentation of ductile metallic rings

In this paper, we numerically simulated the freeexpansion and fragmentation processes of an OFHC ring under an initialvelocity. The conventional Johnson-Cook thermo-viscoplastic constitutivemodel was used to describe the dynamic plastic behavior of the material. TheJohnson-Cook failure model incorporating a cohesive fracture criterion wasused to model the separation progress of the material. ABAQUS/Explicit codewith element erosion was used for the numerical simulations. Multiplesimulations were conducted with a same initial velocity on these meshes,creating a group of fragment samples. The average fragment sizes of eachsample group were obtained. It was found that the Grady-Kipp model based onthe momentum diffusion mechanism gives reasonably close predictions of thefragment sizes; The FEM simulation results show apparent unloading waves(the Mott wave) propagations, confirming that the momentum diffusion didcontrol the 1D ductile fragmentation process.