Influencing Laws of Obliquities/Incident Angles on Ricochet and Trans-ricochet of Projectile-Target Impact for Armor Steel Plate Structural Design

The effectiveness of protective armor supports the projectile ricochet phenomenon as it clearly restrains projectile from penetration and can potentially form basis for design optimization of protective systems. The present numerical study has been carried out to find the most appropriate obliquity/incident angle which can effectively be used for design of protective armor. Although it is not possible to practically control the incident projectile angles, but numerical investigation can potentially provide solution for design and performance optimization of overall structure and surface geometry of target plate, or adaptive adjustment in terms of target obliquity angle. The projectile has been impacted with velocity of 700 ± 20 m/s at incident angles ranging from 15^∘≤θ≤75^∘. The experimental results at 0° has been taken as a reference to validate material model and simulation results. The verification parameters such as eroded mass and steady residual velocity have also been investigated. After all validations and calculations, the window of obliquities/incident angle, safe thickness limit as well as steady residual velocity was obtained. Based on the attained optimum angle 45°, the minimum target plate thickness calculated is 6.4 mm against the thickness of reference plate, 4 mm (UHSLA-XF1700) armor steel. The result was partial penetration at 0° incident angle. The numerical simulation for 6.4-mm-thick target plate under similar circumstances revealed that it has ability to defeat the incoming threat more effectively. For the respective cases of different incident angles, a modified analytical model has also been developed and results coincided with the findings of numerical simulations.