Composites (fibre-reinforced polymers) usually exhibit the best qualities of their constituents and often some qualities that neither constituent possesses. Their main characteristic is a combination of strength and lightness that makes composites the preferred materials in glamorous applications, such as skis, tennis racquets golf clubs, wind surfers, boats, automobiles and aircrafts. Because of the fibre reinforcement, strength of composites is anisotropic with the weakest in the direction perpendicular to the laminate. Failure is often caused by delamination cracks that grow in the interlaminar resin-rich region. The delamination cracks, though mostly invisible on the surface, drastically reduce rigidity of the structure that may lead to catastrophic failure. Research in this area is directed towards understanding the nature of composite delamination and developing methods for improving the delamination resistance.

Two material parameters selected for the study are matrix toughness and fibre-matrix bonding. Effects of the two parameters on the delamination resistance are evaluated at various loading rates, ranging from static to low-speed impact of 5 m/s. Current study is focused on fibreglass for marine applications, with the aim at understanding toughness transfer from matrix to composite.

A new impact tester was designed and built in the Department of Engineering, ANU. The tester is a tool for research in the area of impact response of fibre composites. The tester can specify the input energy and generate a barely-visible-impact-damage (BVID). The energy absorbed for fracture can be measured. Combined with non-destructive techniques, the tester will facilitate the development of new composite materials of high impact resistance.