Investigation on fracture behavior of polymer-bonded explosives under compression using a viscoelastic phase-field fracture method

Polymer-bonded explosives (PBXs) containing the energetic materials embedded in viscoelastic polymer matrix are often subjected to compressive loads in service, such as projectile penetration and drop. This study aims to investigate the fracture behavior of PBXs under compression by implementing a viscoelastic phase-field fracture (PFF) method. The mesh size and characteristic length scale of the present model are determined and further validated by comparing with experimental results. The influence of the viscoelasticity of the polymer matrix and heterogeneous microstructures on the fracture behavior of PBXs is comprehensively discussed. The results show that the strength and stiffness increase with an increasing strain rate; however, the failure strain increases at first and then decreases, which shows typical strain rate sensitivity. It is also found that the size and volume fraction of particulates have different effects on the fracture behavior of PBXs, i.e., the failure strength decreases with the increase of particulate size, but increases with the increase of particulate volume fraction. This study could lay the foundation for optimizing the structural design of high-performance PBXs.