Mechanism-driven analytical modelling of UHMWPE laminates under ballistic impact

Abstract

Ultra-high molecular weight polyethylene (UHMWPE) fiber reinforced composite laminates have been widely used to defend against projectiles and fragments. Although the ballistic performance of UHMWPE composites has been extensively characterized both experimentally and numerically, analytical modelling remains a challenge. This study develops a mechanism-based analytical model of UHMWPE cross-ply laminates, with the progressive process of projectile penetration divided into two sequential stages of local failure and bulging deformation: the former is characterized with the strain concentration model under local shock compaction, and the latter is described using a modified membrane stretching model. Compared with existing energy-based models, the current model enables revealing physical mechanisms underlying the deformation/failure processes of UHMWPE laminate subjected to projectile impact, with relevant parameters correlated with material properties. Further, without using any fitting parameter, the proposed analytical model can predict both the ballistic limit and residual projectile velocity. For validation, the model predictions are compared with existing test data, with good agreement achieved for varying projectile mass, projectile size, laminate type, and laminate thickness. It is demonstrated that the maximum strain under a penetrating projectile is controlled by the thickness of un-penetrated laminate and the growth of bulge, and that the longitudinal wave speed and maximum tensile strain in the UHMWPE laminate dictate its ballistic limit.