Characterization of progressive damage evolution in polymer bonded explosives

Polymer Bonded Explosives (PBX) are particulate composites consisting of stiff brittle explosive grains of different shape and size embedded in soft polymer binder material. When subjected to compression, PBX exhibits a complex mechanical behavior governed by a number of different mechanisms. Besides viscoelastic behavior, inelastic effects caused by grain fracture and debonding of particle interfaces, commonly referred to as damage, can be observed. Experiments have been carried out with various PBX and PBX-like simulant materials. Damage provokes permanent loss of stiffness. Since damage takes place progressively, cyclic compression tests are suitable to correlate the damage progress with loading. Besides stiffness and peak stress, also the post-peak behavior is evaluated. One difficulty, for example, is the separation of damage effects and the nonlinearities caused by the viscoelastic behavior of the binder. Then further modeling aspects are presented to make the experimental results accessible for numerical simulations.