Numerical simulation research on fragments formation of cylindrical cased charge based on SPH method

Abstract

In order to obtain the fracture and fragmentation of a cased charge under blast loading, the JWL equation of state of HMX-based PBX was fitted based on a cylinder test firstly, then the smooth particle hydrodynamics (SPH) method was used to perform a simulation of cased charge under interior blast loading, in the meantime, an blast test of cased charge was conducted. The results show that the parameters of JWL equation of state and the simulation method were reasonably. The simulated fragments velocities and calculated results from empirical formula agreed well with each other, the maximum error did not exceed 9.5%. Under the direct loading of the detonation wave, the fragments velocities increased to more than 1000m/s immediately within 5us, and then the fragments were continuously accelerated by detonation products and shock wave until the fragments reached the maximum velocities in the later 250us. Eventually, the shape of expansion contour of the casing tended to be ellipsoid. The method and results can provide references for the power design of the fragment warhead, as well as the protection design against the fragments.