Initial Study on Constitutive Model of PBXs via Viscoelastic StatisticalCrack Mechanics Including Anisotropic Damage

Building constitutive models that include damage is the foundation for the research of dynamic mechanical responses of explosives.Based on the viscoelastic character on macroscale and the crack directions on mesoscale, we established a viscoelastic statistical crack mechanics including anisotropic damage, and then obtained the simplified constitutive model under uniaxial loading.By using a numerical program, and taking PBX9501 as an example, we analyzed the extension rules of cracks with various directions, and the strength-difference and strain-rate dependence of failure strength and critical strain of explosives.Furthermore, we discussed the sensitivity of 4 main parameters, the crack number density, the initial crack size, the friction coefficient between crack surfaces and the fracture surface energy.The result demonstrates that the 4 parameters greatly affect the extension and evolvement of cracks, which causes the different mechanical responses of explosives.