Dynamic response and microscopic damage mechanism of EFP oblique penetration to the finite aluminium alloy targets

In order to investigate the influence of the impact angle of an EFP warhead on its terminal effects, this research investigates the macroscopic damage effect and microscopic failure mechanism of the aluminium alloy target obliquely penetrated by an EFP warhead with a hemispherical liner. As the impact angle increases, the damage mode of the EFP warhead against the target shifts from perforation to ricochet. The impact angle of 30° can be deemed as the critical angle of the EFP oblique penetration into aluminium alloy target; that is, when the impact angle is less than 30°, the modes of damage and failure caused by the penetration are roughly the same. The ricochet angle of the EFP obliquely penetrating the aluminium alloy target lies between 60° to 75°; that is, when the impact angle is greater than 75°, the ricochet phenomenon occurs after the EFP penetrates the aluminium alloy target obliquely. In addition, the characteristics of the microevolution indicate that the perforation damage from the penetration is derived from the perforation caused by the direct action between EFP and target and the spalling due to the superposed stress waves. In the region of direct action, the metal grains refined under DRX take on directional arrangement mainly in the form of twin crystals, while for the grains in the spalling damage region, the surface abounds with dislocation structures. The research results, coupled with the macroscopic damage effects and microscopic damage mechanism of the metal target, systematically reveal the mechanism of mechanical failure caused by EFP oblique penetration into aluminium alloy targets.