Numerical Simulations of Very Low Velocity Impacts and Ignition of an Explosive Confined by a Thin Case

ABSTRACT Impact experiments carried out at very low speeds on a target consisting of an HMX‐based explosive protected by a thin steel case have recently been published. Reactions are observed for projectiles of a few kilograms and impact speeds of the order of meters per second. These impacts are simulated using finite elements, with a Lagrangian solver and an h‐adaptive mesher. The thermal and mechanical fields are solved at the scale of the structure. The influence of potential sources of heating, such as friction at the projectile/case interface, heating of the projectile itself, and heating by plastic dissipation of the case and the explosive, is studied. For the latter mechanism, heat is assumed to come from the plastic dissipation of HMX crystals. The results show that the geometric configuration of these tests, including the shape of the projectile, leads to a strong deformation of the explosive. The transfer of heat generated by other mechanisms could be neglected.