An optimization scheme for a multilayer armour module against 7.62 mm armour piercing projectile

Abstract

This study presents a methodology to find the optimal sequence and thicknesses of individual material layers in a multilayer armour module. The methodology is demonstrated with application to three different metal alloys: Armox-500T, Ti-6Al-4V and Al-2024. Numerical simulations are performed first to study the ballistic impact behaviour of these three materials using AUTODYN-3D code. The results of numerical simulations are compared with experimental results for validating the numerical models. Thereafter, a three-layer armour module consisting of these three materials is optimized to defeat 7.62 armour piercing projectile with minimum weight. The optimization process involves carrying a set of numerical simulations based on the design of experiment approach to generate a response surface for the ballistic performance of a composite module. A new ballistic performance parameter is introduced to measure the ballistic response of the module by combining depth of penetration and residual velocity of the projectile to bring uniformity between two cases of partial and complete penetration. The proposed parameter provides more information on ballistic performance. The response surface for ballistic performance parameter is generated in terms of thicknesses for six possible combinations of three material layers. The adequacy of the proposed optimization scheme is confirmed with ballistic experiments. The sequence Armox-500T/Ti-6Al-4V/Al-2024 with thicknesses 5.5, 8.5 and 13 mm, respectively, is found to be the best against 7.62 mm armour piercing projectile. Furthermore, the performance of each individual material is compared with an optimized three-layer armour module. The composite module is found to be weight efficient over Armox-500T, Al-2024 and provides better thickness efficiency over Al-2024. The weight efficiency and thickness efficiency of Ti-6Al-4V are found to be comparable to the composite module. This study emphasizes the necessity of developing new procedures to provide reliable estimates of design parameters for a multilayer armour module.