Deformation patterns of steel targets against long rod penetration

An experimental and finite element simulation investigation are conducted to study the deformation patterns of steel targets during the penetration process of tungsten alloy long rods, as well as the influence of strength of the target on the deformation patterns. The experimental results revealed slight mass loss in the first layer of the steel target during the transient entrance phase, with an extremely negligible loss in target mass during the quasi-steady penetration phase. The results of macro-analysis, micro-analysis and simulation show that the eroded target material migrated towards the periphery of the crater, causing an increase in the target's thickness, remained within the target, instead of flowing out of the crater. Therefore, the process of long rods penetrating the metal target is considered as a process of backward extrusion. By combining the backward extrusion theory with energy conservation, a penetration depth model for long rods penetrating a metal target, taking into account both the diameter of the crater and the friction coefficient between the rod and the target, has been established. Although the model is not yet perfect, it innovatively applies the principles of solid mechanics to the study of long rod penetration. Additionally, it takes into account the friction coefficient between the rod and the target during the penetration process. Therefore, this model provides a new research direction for future studies on long rod penetration.