Multi-fragmentation of various metals under dynamic radial expansion

When a cased explosive charge detonates, its metallic envelop inflates because of the expansion of the detonation products until its multiple fragmentation that generates high kinetic energy debris. In industrial and military applications, the spatial distribution of the fragments and their statistics in terms of number, mass, and velocity are mandatory to assess safety or lethality areas. Since the founding works of N.F. Mott (1940’s), numerous experimental, theoretical and numerical studies have been issued on the fragmentation of cased charges or simplified configurations such as hemispheres, cones, cylinders or rings. The present authors recently contributed to this topic designing the PIDRET set-up (plate-impact-driven ring expansion test) that is able to expand reliably thin metallic rings at strain rates close to 10⁴ s^-1. This work will provide new in-situ and post-mortem observations of ring expansion for various metals. Number of fragments and visible necks will be compared to existing analytical approaches such as linear stability analysis (LSA) and Grady’s model.