An analytical model for the ballistic performance of ultra-high molecular weight polyethylene composites

Ultra-high molecular weight polyethylene (UHMWPE) fibers are often used in ballistic armor due to their excellent strength, stiffness, strain to failure, and low density. Despite applicability and growing usage, designing UHMWPE armor systems is challenging. The unique properties of their fibers and matrix materials cause UHMWPE composites to behave differently than other composites. To realize their potential and effectively apply them to armor applications, it is important to understand their failure mechanisms and model their performance without the aid of complicated computer models. This study focuses on understanding their energy absorption and through-thickness failure mechanisms, as well as developing an analytical model to predict ballistic performance. Energy absorption was considered from fiber tensile strain, delamination between layers, matrix cracking, acceleration of the composite mass, and shear failure. Tensile failures from the formation of the deformation cone and out-of-plane compression were considered, as well as shear failure. The analytical formulation predicts the amount of energy absorbed by each mechanism, ballistic limit, duration of the impact event, through-thickness failure distance, and residual velocity. The results were compared with experimental data and good correlation was observed for a range of projectile masses and diameters, as well as composite thicknesses.