Low-Velocity Impact Performance of Indexed Fiber Architecture Ultra-High-Molecular-Weight Polyethylene Plates for Personnel Protection Systems

A flat plate low-velocity impact performance evaluation was conducted on four commercially available ballistic-grade ultrahigh-molecular-weight polyethylene (UHMWPE) materials with three different fiber architectures (suggested by prior ballistic testing at the US Army Combat Capabilities Development Command Army Research Laboratory) and architecture configurations representative of those encountered in thermoformed complex double curvature structures. The four UHMWPE materials encompass a wide range of ballistic-grade materials to represent both fiber and film systems and compliant and stiff matrix binder materials. The three fiber architectures consisted of the reference (baseline) cross-ply architecture, a Helical - 45 architecture (fully quasi-isotropic architecture with a periodicity of 2), and a 50 percent/50 percent combination of the two. The impact samples were evaluated at two impact energies, 50 and 70 J, which directly correlate to prescribed impact velocities defined under blunt impact conditions for combat helmets. The key screening metrics include dynamic peak back-face deflection, displacement contour at peak, and residual dent. The deformation and damage mechanisms per material per fiber architecture were also evaluated to identify the dominant mode of damage.