Experimental investigation of composite lockbolt fastened joints under in-plane low velocity impact

Two different composite fastened configurations, i.e. the filled hole and the single-lap double-fastener joint, are experimentally investigated in tensile mode through different loading rates. The composite material system is the UD carbon/epoxy AS4/8552 and the coupons are fastened with titanium countersunk lockbolts. The experiments are performed in a range from quasi-static to 2.8 m/s impact velocity, using an innovative testing device developed and adapted in a drop tower machine. The main experimental observations are the limited loading rate sensitivity in terms of strength for both tested configurations, the elevated absorbed energy values in the dynamic tests of the lap joint samples, as well as the differences in their failure evolution and modes between quasi-static and impact loading.