Characterization and Modeling of the In-Plane Shear Deformation in Ultra-High Molecular Weight Polyethylene (UHMWPE) Composites

Report No. ARL-TR-8791
Authors: Michael Yeager, Julia Cline, Kari White, Travis Bogetti, and James Sherwood
Date/Pages: September 2019; 27 pages
Abstract: Ultra-high molecular weight polyethylene (UHMWPE) composites are employed in wide array of ballistic protective applications, where there is a close relationship between the as-manufactured component quality and performance. Thermoforming is an efficient way to produce a large volume of complex curvature thermoplastic parts for ballistic protective systems, such as helmets. During the thermoforming process, commercially available thin sheets of UHMWPE material are stacked loosely before undergoing a preforming process at elevated temperature. The near-net shape ?preforms? subsequently undergo high-pressure consolidation. In the preforming process, the individual sheets of UHMWPE composite are subjected to large amounts of in-plane shear deformation. Accurate characterization of the in-plane shear response is critical in developing reliable predictive models capable of guiding process cycle design. This work establishes a methodology for characterizing the in-plane shear response of UHMWPE composites using the bias-extension test method. An LS-DYNA finite-element model, capable of simulating the in-plane shear behavior of the UHMWPE composite, is presented and verified by predicting the results from the bias-extension test. The LS-DYNA model and characterization methodology are further validated through correlation of predicted results with experimental observations using the picture frame test.
Distribution: Approved for public release
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Last Update / Reviewed: September 1, 2019