Analyzing the back-face deformation of curved UHMWPE composite laminate under high-speed impact

Ballistic protection extensively employs curved ultra-high-molecular-weight polyethylene (UHMWPE) laminates to conform to protective targets. However, ballistic tests have indicated that the curvature of laminates increases back-face deformation, diminishing ballistic performance, while the mechanism behind this curvature effect on back-face deformation remains unclear. In this paper, the back-face deformation of curved UHMWPE laminates, including apex displacement and the boundary of the deformation region, are systematically studied through numerical simulation and theoretical analysis. Firstly, a numerical model of curved UHMWPE laminates under the high-speed impact is established. The numerical results indicate that as the curvature increases, the deformation region becomes more concentrated, resulting in a larger apex displacement. Secondly, as the curvature increases from zero, the deformation mode of curved laminates changes from membrane stretching dominated to a combination of membrane stretching and bending. Finally, considering the change in the deformation mode, a theoretical analysis for the propagation of bending waves in an orthotropic curved plate is conducted to reveal the relationship between curvature and back-face deformation. The theoretical analysis shows that increasing curvature slows bending wave speed, reducing in-plane deformation region movement, thus increasing apex displacement. This study is expected to help design curved UHMWPE laminates with better ballistic performance.