Drop Weight Impact Testing of Laminates Reinforced with Kevlar® Aramid Fibers, E-Glass, and Graphite

The instrumented drop weight impact test has been used to study the relative impact damage tolerance of Kevlar®-49 and Kevlar-29 aramid fibers, Thornel®-300 graphite fiber, and E-glass as reinforcements in epoxy-matrix composite materials. Under the conditions of the test, the energy absorbed to failure, defined as the first through crack or the maximum of the load-displacement trace, is proportional to the tensile strain energy to failure of the reinforcing fiber. Thus, the Kevlar fibers, and in particular Kevlar 29, absorb significantly more energy than Thornel 300, while E-glass is intermediate between the two Kevlar fibers. Hybrids with Kevlar 49 and Thornel 300 also absorb more total energy than do all graphite.