High Strain Rate Response of S2-Glass/Epoxy Composites with Polycarbonate Facing

Abstract

Impact damage is of critical concern in structures using laminated fibre reinforced composites. Thermoplastic polycarbonate (PC) offers high impact resistance and is often used in a variety of applications, including the windshield and canopy of aircraft, pressure windows and automotive parts among others. Impact damage to structures utilizing composites has been an area of constant concern. In the current study, S2-glass/epoxy composite laminates bonded to PC (referred to as ‘S2-glass/epoxy-PC’ or ‘Laminate-PC’) have been investigated for their high strain rate (HSR) impact response. A compression Split Hopkinson Pressure Bar (SHPB) with 19.05 mm (0.75”) incident and transmission bars with dynamic recovery technique was used to test four, six and eight layers S2-glass/epoxy-PC samples. Using dynamic recovery technique on the SHPB, the sample was subjected to a controlled single compressive pulse, providing information on damage evolution. The samples were tested under HSR impact in three directions (with respect to the side facing the incident bar of the SHPB). In the first, the PC faced the incident bar, in the second, the S2-glass/epoxy laminate faced the same, whereas in the third, the loading was in the in-plane direction of the laminate. The HSR impact tests were performed by considering three strain rates - 109, 327 and 544/s - for all the experiments. The results of the investigation showed that providing a PC facing to S2-glass/epoxy laminate is an effective way of obtaining deformation in the PC facing which absorbs a large portion of the incident energy, thereby minimizing any delamination threat to the composite backing. PC acts as a sacrificial layer that can be readily replaced in the application.