Simulations of single and double shock experiments using generalized interpolation material point method with a noise control strategy

This paper presents an elaborated discussion on numerically handling single and double shock problems via the implementation of a meshless method, namely the generalized interpolation material point (GIMP) method. Oxygen-free high thermal conductivity copper and aluminum materials were considered. The capability of GIMP to accurately simulate such type of shock wave propagation problem is demonstrated and discussed via the 2-D plane strain solid mechanics formulation. GIMP is a modified material point method (MPM) that has been developed as an excellent numerical tool to solve dynamic problems involving large deformation, penetration, and fragmentation. However, double-flyer impact problem has rarely been simulated by using such a meshless method tool. In this work, the development and implementation of a set of well-tuned parameters are presented for modeling and analysis of both single and double shock experiments. Several procedures, including the discretization effect, were first performed within the GIMP framework to simulate single-flyer impact. Along with a modified update-strain-last method and an elastoplastic Johnson-Cook strength constitutive model, it is observed that the numerical results could be hugely improved when such a full mass matrix noise control strategy was utilized with optimized parameters for the numerical noise control. Thus, large oscillations that occur at the contact interface during high-speed impact can be smeared out without losing significant wave propagation features. Mie-Gruneisen equation of state was introduced to accurately identify the pressure-related shock-induced properties. Artificial defined explicit crack was introduced to model the spall and recompact in double-flyer impact. The simulation results of double-flyer impact problems, including free surface velocity, internal stress, and shock wave propagation presented via spatial-temporal diagrams, were shown to be in good agreement with previously reported data from experiments, finite element method, and analytical calculations.