Blast fragments forming mechanism of a warhead based on modified BW model

Expanding ring is a useful means to study a warhead's blast fragments forming mechanism. Here, through introducing a modified BW cohesive force fracture model's ABAQUS subroutine, the fragmentation process of an expanding ring was simulated numerically. The expanding fragmentation process was divided into four stages. The effects of expanding velocity on fragments' mass distribution and fragments number were discussed. The effects of thickness on the fragmentation mode were also studied. It was shown that the fragmentation process is divided into 4 stages including overall plastic deformation, steady necking, local necking developing and fragmentation; the fragments number increases with increase in the initial expanding velocity and the mass distribution of fragments obeys Rayleigh distribution; the variation of the radius-thickness ratio changes stress status of end deformation stage, the stress of thin shell structures is mainly tensile, while the shear stress status appears in the end stage of thick shell structures, so their fracture modes transfer gradually from tension necking failure to shear failure.