Although they are potentially sensitive, energetic materials are designed to be stable under normal conditions, as well as "weak" mechanical, chemical or thermal loadings. However, under low mechanical loadings, such as low velocity impacts, they may react untimely. Propellants and especially the butalite, object of our study, show "reactions" to impact velocities below 100 m.s-1, whose origin is probably related to the material microstructural damage. In this context, the ultimate goal of CEA Gramat is to obtain a predicting tool for the vulnerability of energetic materials for low velocity impacts as drop weight test. So it is essential to have data on the morphology and macroscopic thermo-mechanical behavior, its component phases at the mesoscopic scale and its interfaces. Thus, the objective of the thesis is to determine the type and the damage(s) level(s) generated in an "inert butalite", during a low velocity mechanical impact (i.e., less than 100 m.s-1), using a fast camera recording and ante- and post-test microtomographic analysis, or by studying the physical phenomena which are at the origin of reactions, their evolution and physical origin(s). Grains are represented by a purely elastic model and HTPB matrix is described by a visco-hyper-elastic model (coupling a Prony serie and Mooney-Rivlin model).
Mesoscale Analysis of dynamic loading and their physical consequences on a propellant: numerical and mechanical modelisations issues