Dynamic response of UHMWPE plates under combined shock and fragment loading

Ultra-high molecular weight polyethylene (UHMWPE) fiber composite has been extensively used to construct lightweight protective structures against ballistic impacts, yet little is known about its performance when subjected to combined blast and fragment impacts. Built upon a recently developed laboratory-scale experimental technique to generate simulated combined loading through the impact of a fragment-foam composite projectile launched from a light gas gun, the dynamic responses of fully-clamped UHMWPE plates subjected to combined loading were characterized experimentally, with corresponding deformation and failure modes compared with those measured with simulated blast loading alone. Subsequently, to explore the underlying physical mechanisms, three-dimensional (3D) numerical simulations with the method of finite elements (FE) were systematically carried out. Numerical predictions compared favorably well with experimental measurements, thus validating the feasibility of the established FE model. Relative to the case of blast loading alone, combined blast and fragment loading led to larger maximum deflections of clamped UHMWPE plates. The position of the FSP in the foam sabot affected significantly the performance of a UHMWPE target, either enhancing or decreasing its ballistic resistance. When the blast loading and fragment impact arrived simultaneously at the target, its ballistic resistance was superior to that achieved when subjected to fragment impact alone, and benefited from the accelerated movement of the target due to simultaneous blast loading.