Numerical analysis of flyer plate experiments in granite via the combined finite-discrete element method

In this study, the combined finite-discrete element method (FDEM), which merges the finite element-based analysis of continua with discrete element-based transient dynamics, contact detection, and contact interaction solutions, is used to simulate the response of a flyer plate impact experiment in a Westerly granite sample that contains a randomized set of cracks. FDEM has demonstrated to be a strongly improved physical model as it can accurately reproduce the velocity interferometer system for any reflector plot and capture the spall region and spall strength obtained from flyer plate experiments in granite. The number and the distributions of preexisting fractures have also been studied to get better understanding of the effect of structural cracks on the mechanical behavior and the failure path of Westerly granite under high strain rate impact. These FDEM capabilities, in the context of rock mechanics, are very important for two main reasons. First, the FDEM can be further applied to many complex large-scale problems such as planetary impact, rock blasting, seismic wave propagation, characterization of material failure around explosive crater formations, and detection of hydrocarbon flow in petroleum industry. Second, it can be used to validate high strain rate impact experiments and essentially, via virtual experimentation, replace these high-cost experiments by very cost- and time-effective simulations.