BALLISTIC IMPACT RESISTANCE OF SMA AND SPECTRA HYBRID GRAPHITE COMPOSITES

The effect of adding small amounts of high strain hybrid components on the impact resistance of graphite epoxy composites subjected to proje ctiles traveling at ballistic velocities (greater than 900 ft/sec) has been studied. The hybrid components tested include superelastic shape memory alloy (SMA) and a high performance extended chain polyethylene (ECPE) known as Spectra(TM). In all cases, the embedded SMA fibers we re pulled through the graphite without straining to their full potenti al. It is believed that this is due to high strain rate effects couple d with a strain mismatch between the tough SMA and the brittle epoxy r esin. However, a significant increase in energy absorption was found b y adding ECPE and ECPE/SMA layers to the backface of the composite.