Dynamic damage and fracture of a HMX based PBX
Résumé
The French Commission for Atomic and Alternative Energies is interested in the predictionof the ignition of energetic materials that experience low velocity impacts. The ignition mecha-nism for such loadings is described as non-shock ignition and is localized at the structure microscale. Among the attempts to explain such ignition, the micro cracks friction is suspected. Atthe structure scale, continuum damage mechanics in dynamics is well appropriated to model theproblem. However, one of the major difficulties in the numerical simulation of damage is due tothe localization phenomenon.In the experimental part of the study, a reversed edge-on impact test has been developed toobtain an initial view of the microstructure (large crystals embedded in a "dirty binder") andreal-time and post-mortem observations of the deformation of the microstructure when submittedto static or dynamic loadings [1-2]. Images highlight the behavior of the matrix/grain interface.Decohesion is observed without tangential friction and hot spot formation is thus excluded inthese interfaces. Depending on the loading conditions (for example of the confinement), thestiffness of the matrix evolves and plasticity and microcracking can be observed into the largercrystals. The location and the possible hot spot formation mechanisms will be discussed.J. Vial, D. Picart, P. Bailly, F. Delvare, Numerical and experimental study of the plasticity ofHMX during a reverse edge_on impact test, Modelling, Simul. Mater. Sci. Eng. 21, 045006,2013.K. Serafin, D. Picart, P. Bailly, Development of an impact test to study the hot spot formationin PBX, in NTREM 2017, Pardubice