Investigation on the penetration resistance of aluminum plates against high-speed square projectiles using a new physical damage model

The penetration resistance of aluminum plates against square projectiles has emerged as a critical research focus in impact engineering. In our study, experimental analyses were conducted using a ballistic gun system. Numerical simulations were performed using an advanced physical damage model incorporating dynamic void evolution. Our new model exhibited excellent prediction performances in ballistic limit velocity (the maximum error is 7.74%) and residual velocity (the lowest R-value is 0.8803). The effects of width-thickness ratio for square projectile, plate thickness, and material properties on ballistic performance were evaluated. The results revealed that localized shear plugging was the dominant failure mode in aluminum plates penetrated by square projectiles. Increasing the square projectile velocity led to a change in fracture morphology from square to circular, accompanied by a marked expansion of the penetration area. Comparative studies highlighted the high prediction accuracy in ballistic limit velocity of our proposed model compared to traditional phenomenological models (the maximum error is 14.99%) and physical models (the maximum error is 65.99%). Parametric investigations using our validated model examined the influence of projectile characteristics on penetration performance. Among projectiles with the same mass, cubic projectile exhibited the optimal penetration performances, while spherical projectile was the worst. Moreover, the penetration performance between square and cylindrical projectiles was solely determined by their contact area with the plate, and was independent of their cross-sectional shape. Our model provided an effective new method for analyzing penetration mechanisms. Our findings provided significant insights for damage assessment of warheads and the design of protective structures.