Simulating hypervelocity impact with a discrete element approach

We present new developments to a discrete element model designed to simulate hypervelocity impacts between on-orbit satellites and space debris. The advantage of the discrete element-based simulation method is its ability to accurately model fragmentation which always accompanies a hypervelocity impact event. As previous work showed the model's ability to accurately simulate hypervelocity impact fragmentation at very high impact velocities, our focus in this paper is predominantly on improving the model's behavior at lower velocities. These low-velocity secondary-impacts also play an important role in determining the final distribution of fragments following a hypervelocity impact event. We achieve this by enhancing our discrete element model's bonding structure to more accurately simulate a continuum material. We evaluate the enhanced model's performance with a variety of simulations ranging from tension tests to hypervelocity impacts. Parameters for the model are calibrated for the whole range of impact velocities using well know ballistic limit equations. Three large impact simulations are presented which demonstrate the model's capabilities in capturing the full range of fragment sizes. The satellite breakup simulation results are compared to the NASA breakup model and show very good agreement.