Impact Response of PBX 9501 Below 2 GPA

DDEM2, a discrete element code, is used to model plane shock-wave profiles in unreacted PBX 9501. The constitutive properties of the material are modeled in terms of hydrostatic pressure and viscoelastic shear stress. The former is modeled using Hugoniot data. The latter is represented by a relaxation functional, which is approximated by a three-term Prony series. Material parameters were found to give a satisfactory fit to the measurements. The relaxation times are 1x10(-7)s, 1x10(-6)s, and an elastic assumption. A single shear modulus is reintroduced at the beginning of unloading. The unloading elastic component is 5x10(10) dynes/cm(2) and the relaxation time is 4x10(-7)s.