Comparison of hypervelocity fragmentation and spall experiments with Tuler–Butcher spall and fragment size criteria

The present investigation compares predictive theories of dynamic spall and fragmentation with previously reported experimental data. In the experimental tests, aluminum spheres normally impacted thin aluminum plates at over approximately 4.5–7.5 km/s. Scaling features of the impact breakup phenomenon were explored through selected variation in sphere size and plate thickness. The principal diagnostic was high-resolution flash radiography. Fragment-size features of resulting fragment clouds were determined through detailed analysis of the recorded radiographs. Other investigators have measured the spall strengths for aluminum at comparable ultra-high strain rates. Spall strength amplitude and the corresponding strain rate dependence are principal results of the study. Existing dynamic fracture criteria are specialized here to the sphere impact spall and fragmentation event, and compared with empirical data. Velocity and strain rate scaling relations are developed for fragmentation size in the sphere impact event.