Experimental and numerical studies of ballistic resistance of hybrid sandwich composite body armor

Defense mechanisms remain important and indispensable due to the different types of pistols and ordnance besides many guns. Hybrid composite sandwich panels are an attractive focus because of their ingrained characteristics, such as high stuffiness and high energy absorption. Hybrid composite sandwich panels are among the most important in armoring various structures. Despite the high density of these panels, they have significant qualities that qualify them to be the first selection for use in armored vehicles or body armor. Recently, there have been several types of structures, and selecting the appropriate structure as armor against the projectiles is very important. The study subjected three samples to the ballistic impact test using a 7.62 x 39 mm bullet. The first sample, S1, consists of ultra high molecular weight polyethylene (UHMWPE)/epoxy, unfilled honeycomb core, Kevlar/epoxy, unfilled honeycomb core, Kevlar/epoxy, and UHMWPE/epoxy; the second sample, S2, comprises Kevlar/epoxy, unfilled honeycomb core, Kevlar/epoxy, unfilled honeycomb core, and UHMWPE/epoxy, and the third sample, S3, comprises Al2O3, Kevlar/epoxy, unfilled honeycomb core, carbon/epoxy, unfilled honeycomb core, and carbon/epoxy. ABAQUS software was used to evaluate the ballistic impact numerically, and after that, the study examined the same armor samples experimentally. The results manifested that only the armor S3 succeeded in stopping the bullet. This is attributed to the structure of the cores, which helps compress and accumulate the cells under the projectile. The speeds of the bullet after penetration (residual velocity; VR) were 748.5 and 715.3 m/s for S1 and S2 armors, respectively, where the back face signature for S3 was 1.5 mm, which is optimum and within the allowed range. The total energy absorption of these armors S1, S2, and S3 is 344.65, 539.04, and 2585.66 J. Furthermore, the highest deviation between numerical and experimental approaches is about 2.04% in the VR.