S-2 glass composites can readily serve as backing materials for armor systems due to their light weight and tensile properties. However, high-fidelity ballistic modeling of these composites requires accurate predictions of their nonlinear deformation and failure behaviors, which can prove challenging. This paper describes simulations of a plain-weave S-2 glass composite at the mesoscale using a mesh geometry that individually models the S-2 glass yarns, epoxy resin matrix, and yarn/matrix interfaces as separate entities. Simulation results are compared to a wide variety of mechanical tests designed to measure the response of the composite to tension, shear, and delamination. Although the individual yarns, matrix, and interfaces are described using relatively simple material models, the overall composite model can accurately reproduce behaviors such as nonlinear deformation, yarn breakage, and delamination in both tension and shear.

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The deformation response of welded aluminum plate was evaluated at high and low strain rates. Mechanical and ballistic experiments were conducted on 2.5 cm thick samples obtained from full penetration welds for welded aluminum 5083-H131 plate. Similar experiments were also conducted for the aluminum 5083 alloy as a baseline for comparison. Experiments were designed to compare the deformation response and ballistic performance differences for fusion welds versus friction stir welds. The fusion welds were processed using gas metal arc welding. The low strain rate deformation response was evaluated with three-point bend tests at an approximate strain rate of 1 s-1. The high strain rate response of the three materials was assessed using ballistic impact experiments at a range of velocities. Digital image correlation analysis was applied to gain insight into the deformation response through quantification of the strain and deflection profiles. The deformation response differences are compared for the welds versus the baseline aluminum alloy.

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