Computational analysis of temperature rises in microstructures of HMX-Estane PBXs

The thermomechanical response of HMX/Estane, a polymer-bonded explosive (PBX) is analyzed for initial temperatures between 210 and 300 K. The main objective of this analysis is to gain a better understanding of the concepts that lead to deformation and heating of energetic composites as they undergo mechanical and thermal processes subsequent to impact. A recently developed cohesive finite element method (CFEM) framework is used to study the microstructure-level response of PBX. The CFEM framework allows the contributions of individual constituents, fracture and frictional contact along failed crack surfaces to heating to be tracked and analyzed. Digitized micrographs of actual PBX materials are used. The issues studied include large deformation, thermomechanical coupling, failure in the forms of microcracks in both bulk constituents and along grain/matrix interfaces, and frictional heating. The focus is on the correlation between grain-level failure mechanisms and overall temperature rise in the PBX. The results are used to establish microstructure-response relations that can be used in the design of energetic composites.