2D-Wedge Impact Response of Film-Based UHMWPE Composites as a Function of Loading Rate and Indenter Geometry

Author(s):

C. Allan Gunnarsson and Tusit Weerasooriya

Abstract:

An experimental method was developed to obtain the rate-dependent deformation and failure response of ultra-high-molecular-weight polyethylene (UHMWPE) composites during penetration while allowing for strain measurements of the response that are traditionally unavailable during ballistic experiments. The composites were fabricated using solid-state extruded unidirectional films. The loading rate varied from low-rate indentation to high-rate impact using a modified split-Hopkinson pressure bar. Different deformation and failure mechanisms were observed by varying the indenter geometry and specimen boundary conditions. Indenter geometries ranged from blunt (for tension and compression dominated stress state) to ultra-sharp (razor blade) for shear cutting dominated. Boundary conditions included the unbacked configuration, in which the specimen backface was unconstrained, and the backed configuration, where specimen motion was constrained. The experiments enabled measurement of the strain profile ahead of the indenter during loading. The deformation and failure responses were dependent on indenter geometry, with higher sharpness corresponding to lower loads, as well as boundary condition, with the unbacked configuration dominated by bending while the backed configuration was dominated by shear cutting and transverse sliding. These experimental findings address a critical knowledge gap and have been used to develop ratedependent deformation and failure computational concepts that incorporate mechanism-based multiaxial deformation and observed dominant failure modes.