Experimental study on the blast resistance of polyurea-coated aramid fabrics

This paper investigates overpressure attenuation capacity and failure mechanism of the polyurea-coated aramid fabric (PCAF) subjected to air-blast loading experimentally. The peak overpressure, arrival time and positive pressure duration of shock waves on the blast and back side of PCAFs were obtained in tests and analyzed. In addition, the failure mode and mechanism were revealed with the electron scanning microscope (SEM), meanwhile the effect of polyurea type, coating position and thickness ratio on the blast resistance were discussed. The results show that in the cases of scaled distances of 1.84 and 2.32 m/kg^1/3, PCAFs, one-layer polyurea coated on three-layer aramid woven fabrics, can attenuate the peak overpressure by about 70 %, delay the arrival time by about 0.7 ms, and shorten the positive pressure duration by 10 %-50 %. This is due to the increased out-of plane stiffness and closure of interweaving apertures of the aramid fabric. Furthermore, perforation is the main failure mode of aramid fabrics, in which the tensile breakage in weft yarn and the frictional slip in warp yarn, while the failure modes of PCAF mainly include fracture and exfoliation, with both weft and warp yarns breakage and polyurea failure. It was concluded that the degree of infiltration between the polyurea and fabric affects mechanical properties of the fiber, changing the failure mode of PCAF. In terms of the extent of damage, the PCAF exhibits a superior blast resistance when the polyurea coated on the back side. The blast resistance of PCAF increases first then decreases with an increase in the thickness of the polyurea layer under the same areal density.