Mechanical Loading Dependence on Burning Surface Areas

ABSTRACT The transition from normal (surface) to abnormal (convective) burning modes of explosives is still a difficult phenomenon to model. This transition, which yields the acceleration of the combustion propagation, could result in a violent reaction. Nowadays, abnormal burning is interpreted as an increase in burning surface area. The latter depends on the initial state of the microstructure and therefore of the mechanical history. This paper considers the coupling between the combustion of HMX‐based polymer‐bonded explosives and its previous mechanical loadings. The experimental set‐ups used to (1) apply a triaxial compression (that mimics the mechanical fields experienced by the explosive composition when submitted to a Steven test) and (2) burn the samples in a closed vessel will be described. Experiments show a strong dependence on the critical pressure leading to abnormal combustion on a previous mechanical loading. An analytical model is proposed to determine the real‐time burning surface area during combustion. It enables modelling of the increase in surface area increase when the critical pressure is reached. Experimental results and surface determinations are presented in this paper. Future works will be discussed.