Discrete element method contact model for dynamic simulation of inelastic rock impact

A contact model for inelastic impact-rebound events such as those that occur when a rock bounces down a slope is developed for dynamic simulations using the discrete element method. Upon impact, the normal contact force follows a linear elastic relationship as a function of relative displacement up to a pre-set transition force, after which the contact force is fixed at the transition force until the relative velocity between the objects in contact reaches zero. Upon unloading (rebound), the contact force follows a power function that enables the contact model to remove, in a time-stepping manner, significant stored elastic energy from the contact thus reducing the rock's kinetic energy. The model automatically generates lower values of coefficient of normal restitution as the impact velocity increases.