Self-sharpening penetration model of tungsten high entropy alloy

Long-rod projectiles (LRPs) with deep penetrability have been widely used in the defense industry. LRPs made of self-sharpening materials can maintain a sharp head due to the formation of shear bands during the penetration process, which greatly improves their penetrability. However, due to the complexity of extreme conditions, the mechanism of self-sharpening penetration is still unclear. Here, a semi-fluid self-sharpening penetration model that includes the self-sharpening effect is proposed. The model reveals that the self-sharpening effect can effectively enhance the penetrability by reducing the expansion resistance of the target and the deceleration of the projectile. The penetration depth predicted by the theoretical model is in good agreement with the experimental results. It is further found that the disappearance of the self-sharpening phenomenon as the penetration speed increases is determined by the competition between shear band propagation and projectile erosion. Furthermore, it is revealed that projectile materials with high Johnson damage number, low Eckert number, and high Prandtl number were identified as more prone to exhibiting self-sharpening behavior. This may provide some new insights for designing self-sharpening heavy alloy and developing advancing LRPs.