Experimental investigations on composite, fibre-metal and metal coupons for high velocity bird impacts

Bird strikes on aircraft are well known and cases exist of such strikes causing extensive damage and even loss of aircraft. While aluminum has been used widely for a number of years for structural components subjected to bird strike, there is interest in using composites and fibre metal laminates in recent years. The need to use these advanced materials has been driven by their distinct advantages in terms of reduction of parts, lower weight, higher fatigue resistance and ability to keep shape when impact loads are low. Energy absorption under high velocity impact by a bird (soft body) is complex due to the highly non-linear effects that occur and the failure modes that can be associated with the materials. It was found appropriate to carry out coupon level impact studies using an airgun, through which soft bodies representing the\ud bird in the form of gelatin cylindrical masses were fired at high speeds. Various coupons of carbon fibre composites,\ud fibre-metal (using aluminum, glass and carbon) and metal were fabricated and tested. Data from these tests were\ud analyzed to evaluate the energy absorption. Interesting behavior was found in the fibre-metal laminates, which showed failure mechanisms that were a combination of composite and metal, retaining integrity that would have been expected from metal coupons while having higher energy absorption