Low-velocity impact and damage of a pressed high explosive

In the context of the safety of pyrotechnic structures, the evaluation of the violence of reaction due to thermal or mechanical aggressions (impact) is required. Nowadays, there is no unified approach approved by the international scientific community to describe the complex processes involved in a Combustion-Deflagration-Detonation transition. The first stage of the transition i.e. the burning rate and normal/abnormal critical pressure deeply depends on the microstructure of the explosive. Therefore, parameters such as crack density, crack length and number of fragments must be predicted by numerical simulations. In the first part of the study, a Steven-Test target has been impacted just below the reaction threshold. It has enabled analyzing the microstructural state of the explosive (micro-cracks density, porosity…). This test has then been simulated using a mechanical constitutive law. The damage evolution law is built on original defects density and the activated cracks density. Cracks propagate in Mode I. This anisotropic damage model has been fitted to mechanical data obtained on a HMX-based explosive. A first comparison between the experience and simulations is proposed.