Abstract: Cross-plied unidirectional Ultra-high molecular weight polyethylene (UHMWPE) sheets is the main material for the production of soft body armor. At first, the tensile behavior, in-plane shear behavior and punch-shear behavior of UHMWPE sheets under quasi-static loading were studied using experimental method. The experimental show a sudden brittle fracture occurred in the quasi-static tension process, the tensile strength is about 641MPa. A highly non-linear behavior of force-displacement curve was observed during in-plane shear process, plastic hardening occurred in the direction of the tension force and matrix shear failure is the main failure mode. After failure, the angel between fibers in adjacent plies has reduced from 90° to 74°. The through-thickness shear strength is about 168MPa, which was obtained using a set of special clamp. Then shell elements were adopted to establish the finite element model for studying the tensile experiment and punch-shear experiment process numerically. The numerical results are in good agreement with the tensile experiment results in maximum tensile force, tensile strength and failure strain, and the stress contours in the UHMWPE sheets were also obtained; The stress history of elements in the shear failure area were captured using numerical method.

Key words: UHMWPE, tension, in-plane shear, punch-shear, FEM