Analysis of Composition B Sphere Impact Fragmentation Experiments
Since energetic material fragmentation governs the surface area available for burning and potential escalation to violent reaction modes (e.g., deflagration-to-detonation transition and XDT modes), it is critical that hazard response models accurately capture impact damage response. The objective of this work is to analyze recent Composition B sphere impact experiments conducted by Naval Air Warfare Center Weapons Division (NAWCWD) that probe fragmentation response for impact speeds from 27 to 127 m/s. In those experiments, fragment size distribution was measured by dry sieving damaged samples. A power law relationship was developed for the normalized cumulative fragment number as a function of the normalized fragment mass, (N/ N$_{tot}$ = A (M$_{bin}$/ M$_{avg}$ ) n , across all impact speeds. The power law fits demonstrated good agreement with the experimental data. We also correlated the power law fitting parameters to the impact speed. The power law prefactor, A, obeyed a polynomial relationship while the power law exponent, n, obeyed a linear relationship in impact speed. While this preliminary analysis shows good agreement with Composition B fragmentation data, it was based on experiments over a limited range of impact speeds and a single sample size. Future modeling-based studies are critical to improve our understanding of fragmentation response and to more confidently extrapolate to larger length-scales and higher impact speeds.