Two critical damage parameters for the dynamic tensile fracture of ductile metals

A concept of critical fracture in the dynamic tensile spall has been developed via percolation model and two physical parameters, named as the critical linking damage Dl and the critical fracturing damage Df, are proposed. Dl indicates the critical value of damage for the onset of void coalescence, and Df the critical value for the occurrence of catastrophic fracture. With experimental measurements of the free-surface velocity profiles and the numerical simulations, we demonstrate that these two critical damage parameters are independent on the impact stress and the tensile strain rate, and it is also applicable to predicting the dynamic tensile fracture behavior in metal cylinders. Therefore, we may regard these parameters as the material constants to identify the intrinsic characteristic of the dynamic tensile fracture in explosion and shock wave events.