Characterization of microscopic damage due to low-velocity and high-velocity impact in CFRP with toughened interlayers

<p>In this paper the low-velocity and high-velocity impact damage in a carbon fiber reinforced plastic (CFRP) laminate with toughened interlayers was experimentally characterized. The low-velocity impact test was carried out by using a guided drop weight system while the high-velocity impact test was conducted by using a high-velocity impact testing machine. The damage in the laminate was then observed using optical microscopy and soft X-ray radiography. It was revealed from the observation that microscopic damage state and damage area varied with the impact velocity. The variation is ascribed to the fact that the low-velocity impact causes global deformation while the high-velocity impact energy is absorbed mainly by damage due to local deformation. Although the toughened interlayers suppress delamination for low impact energy, the high interlaminar fracture toughness sometimes causes the transition of interlaminar delamination to intralaminar one.</p>