Simulation and measurement of fragment velocity in exploding shells

This paper presents simulations of initial velocity distribution of fragments for non-trivial shapes of casing in exploding shells, using a semi-empirical computational model. The key to the proposed approach is the use of transformation of a general geometrical shape to a hollow sphere followed by an application of Gurney principles in the transformed domain. The model is validated against an analytical model for a finite cylindrical charge bounded by a cylindrical shell and identical end-plates. A computation for 105-mm shell with steel casing and aluminium fuze illustrates aspects involved in reliable comparisons of fragmentation models against a standard trial data. Further, a simple and inexpensive experimental procedure based on a pin gauges measurement is described. Measurements obtained for short cylinders and an 81-mm mortar bomb are compared with numerical predictions. The described model responds to the need for an improved, fast assessment tool applicable to practical designs involving geometrically complex multi-material shells. The results highlight a requirement for quality experimental data obtained for complex shapes.