Fragment velocity distribution of D-shaped casing with multiple fragment layers

•The D-shaped casings with different fragment layers number were tested.•The velocity distributions of the casings were obtained by X-ray radiography.•A theoretical model was set up to analyze the energy dissipation of the fragments.•The multiple layer fragments will suffer severe energy dissipation. Asymmetric casings filled with explosive have attracted increasing attention in innovative warhead design (e.g. aimable warhead) and improvised explosive device protection. Previous research showed that greater damage could be realized to the target with the fragment cluster from multiple fragment layers than from a single fragment layer. As a typical asymmetric casing, D-shaped casing has been used in deformable aimable warhead, deployable aimable warhead as well as warhead in hypersonic weapons. To assist in the design of asymmetric warhead, this work examined the velocity distribution and impact performance of fragments cluster from the D-shaped casing with multiple fragment layers. The fragment velocity distribution and fragment dispersion of the D-shaped casing with different fragment layers were experimentally analyzed. In addition, the effects of fragment layer on the distribution of fragment velocity were analyzed by comparing theoretical model and experimental results. Experimental and theoretical analysis showed significant energy dissipation from the collision and friction between fragments, and the dissipated energy increased obviously with rising number of fragment layers. The findings herein could serve as a reference for further investigations of multi-layer fragment structures and provide a foundation for asymmetric warhead design.