Enhancement of UHMWPE encapsulation on the ballistic performance of bi-layer mosaic armors

The ballistic performance of a bi-layer armor encapsulated with ultra-high molecular weight polyethylene (UHMWPE) composite laminate was investigated using a combined experimental and numerical approach. Three series of test specimens were examined: (A) bare and encapsulated aluminum (Al) plates, (B) bare and encapsulated bi-layer mosaic armors, and (C) bi-layer mosaic armors having identical areal density but different encapsulation thicknesses. The ballistic behaviors and failure mechanisms of UHMWPE encapsulated Al plates and bi-layer mosaic armors under different projectile impact velocities were analyzed systematically. Attributed to the integration effect of encapsulation, the encapsulated specimens could effectively disperse localized projectile impacting to the entire structure. The results indicated that the UHMWPE encapsulation could enhance significantly the ballistic resistance of traditional ceramic/metal bi-layer armors, due mainly to serious pulling and stretching deformations of the lateral and rear UHMWPE laminates in resisting the projectile impact. However, thicker encapsulation would not necessarily lead to better ballistic performance for specimens with equal areal density. Further, the thickness (or mass) ratio of the armor substructures needed to be tailored synthetically to achieve optimal ballistic performance.