Lightweight polyethylene non-woven felts for ballistic impact applications: Material characterization

The polyethylene non-woven felt, Dyneema Fraglight, has excellent capabilities to stop bomb fragments. According to the manufacturer, a felt with an areal density of 1.2 kg/m2 stops a 17-grain projectile at 450 m/s. The research presented in this paper aims at improving our understanding of how non-woven felts work. Static tensile tests were performed at different strain rates and temperatures. The static tensile tests showed that there is an important size effect: the strength of the specimens decreases when increasing the size of the specimen, for lengths of 5 cm or less. This effect is expected since the felt is made by mixing, combing and needle punching of 5-cm-long fibers. The tests also showed that the felt is anisotropic and that at a temperature of 100 °C it loses a significant part of both its strength and strain to failure. Tensile tests at medium (1 s−1) and high strain rates (1000 s−1) did not show any evidence of strain rate dependence. Out-of-plane punching tests, designed to help with the modeling, were also performed and the results are presented.