Experimental Study on Impact-induced Initiation Thresholds of Polytetrafluoroethylene/Aluminum Composite

Impact experiments were conducted with a gas gun to investigate the impact-induced initiation thresholds of a polytetrafluoroethylene/aluminum (73.5 wt % and 26.5 wt %) composite. Targets of steel, aluminum, and low-density polyethylene materials and sample rods of four different lengths were used to decouple the effects of impact pressure and loading strain rate. By subjecting the samples to different loading conditions, it was shown that the impact-induced initiation of polytetrafluoroethylene/aluminum is decided by the impact pressure and the loading strain rate simultaneously. The impact pressure and strain-rate thresholds for initiation were arrested by the experiments. A 30° inclined steel target was used to produce a compression-shear configuration as a comparison with the normal impact experiments. The initiation was more likely to happen; it demonstrated a shear-induced initiation mechanism, and a lower initiation strain-rate threshold was observed under oblique impact. Based on the experimental results, two theoretical curves were proposed to predict the impact-induced initiation of polytetrafluoroethylene/aluminum under normal and 30° oblique impact.