The effect of material variability on the products equation of state for HMX-based PBX 9501 high explosive

The detonation performance of high explosives (HEs) is typically characterized via the cylinder expansion test (CYLEX). This test is intended to diagnose the ability of the steadily-detonating cylindrical HE charge to accelerate the surrounding copper tube. In its modern iteration, the imparted wall velocity is measured via Photon Doppler Velocimetry (PDV) and additional diagnostics are used to determine the HE detonation wave’s velocity and front curvature. These data then form the basis for hydrocode-informed, highly-accurate model reductions of the explosive’s products equation of state (EOS). For HMX-based PBX 9501, the effect of material variability of this important constitutive model parameter has not been fully characterized. To this end, we analyze four recent CYLEX tests using PBX 9501 charges derived from different source lots of molding powder and spanning a wide range of pressing age (from 1 to nearly 40 years). These tests are specifically reduced using an advanced multi-material hydrocode-based calibration methodology. The resulting products EOS models then help quantify and dimension the effect of the described material variability on the explosive’s energy release characteristics.