Structural response analysis of free rigid-perfectly plastic warhead under three typical transverse loads

Abstract

Based on the rigid-perfectly plastic assumption, the structural response of a free warhead under the application of concentrated force, evenly distributed force, and ramping-up force was analysed, taking the geometrical features into account. By the sectional shear force and bending moment distribution, the critical section was determined through a yield criterion based on the fully plastic bending moment. It shows that when the load is applied at the tip of the warhead, singularity occurs in the yield function at the tip, but vanishes when the applying (or starting) point of the load some distance away. The influence of the distance of the applying (or starting) point to the tip was also discussed, and was found to be important in determining the location of the critical section. As the applying (or starting) point moves away from the tip, the critical section appears near the tip first, then jumps to the cylinder part of the warhead, and when far enough, jumps back to the head of the warhead in the concentrated force case, while in the distributed force cases the critical section appears first at the cylinder part, and then jumps to the head. The critical section jumps to the head much earlier and more localized around the connecting point of the head and the cylinder in the ramping-up case than in the evenly distributed case.