Effects of heat-induced damage on impact performance of epoxy laminates with glass and flax fibres

The knowledge of impact behaviour of heat exposed composites is very limited, even though this could be one of the critical issues for many practical applications. Therefore, the current study was conducted to investigate the effect of preheating on the impact performance of glass and flax fibre reinforced composite laminates by a comprehensive set of experiments. The composite laminates were partially damaged by heat convection (using a fan assisted furnace) and their impact properties, such as force and energy absorption, were measured under a low velocity (1.85 m/s) impact loading situation. The impact test results showed that the heat exposure at 300 °C increased the energy absorption of the glass fibre composites but reduced those of the flax fibre composites. Furthermore, an addition of ammonium polyphosphate, as a flame retardant, also incremented the absorbed energy of the heat exposed composites and significantly reduced the heat release rate, resulting in an acceptable vertical burning behaviour, that meets the aviation standard requirements.