The durability of graphite/epoxy laminate subjected to repeated low velocity impact

Low velocity impact has been considered as quasi-static loading, as the dynamic effects are decaying before the pressure reaches its maximum. However, when the impact energy is low enough as not to cause visible damage, the dynamic effect at the beginning of the impact may cause internal damage to the laminate. Laminates were loaded quasi-statically and by impact to the same bending strain and with the same indenter shape several times. The laminates that were subjected to the impact loading failed much more rapidly. Analysis of the problem shows that the stress waves created by the impact at the beginning of contact intensify the damage zone created by the preceding impact until the final failure occurs.