High strain rate response of S2-glass/epoxy composites with polycarbonate facing

Impact damage is of critical concern in structures using laminated fibre re inforced composites. Thermoplastic polycarbonate (PC) offers high impact re sistance and is often used in a variety of applications, including the wind shield and canopy of aircraft, pressure windows and automotive parts among others. Impact damage to structures utilizing composites has been an area o f constant concern. In the current study, S2-glass/epoxy composite laminate s bonded to PC (referred to as 'S2-glass/epoxy-PC' or 'Laminate-PC') have b een investigated for their high strain rate (HSR) impact response. A compre ssion Split Hopkinson Pressure Bar (SHPB) with 19.05 mm (0.75") incident an d transmission bars with dynamic recovery technique was used to test four, six and eight layers S2-glass/epoxy-PC samples. Using dynamic recovery tech nique on the SHPB, the sample was subjected to a controlled single compress ive pulse, providing information on damage evolution. The samples were test ed under HSR impact in three directions (with respect to the side facing th e incident bar of the SHPB). In the first, the PC faced the incident bar, i n the second, the S2-glass/epoxy laminate faced the same, whereas in the th ird, the loading was in the in-plane direction of the laminate. The HSR imp act tests were performed by considering three strain rates - 109, 327 and 5 44/s - for all the experiments. The results of the investigation showed tha t providing a PC facing to S2-glass/epoxy laminate is an effective way of o btaining deformation in the PC facing which absorbs a large portion of the incident energy, thereby minimizing any delamination threat to the composit e backing. PC acts as a sacrificial layer that can be readily replaced in t he application.