Low energy impact behaviour of polyester-glass composites formed by resin transfer moulding

The impact behaviour of polyester-glass composites formed by resin transfer moulding has been studied to determine the effects of glass content, laminate thickness, and reinforcement geometry on damage developed during a low energy (9.56 J) subcritical impact. The force time responses of composites containing bidirectional and random reinforcements were analysed in terms of an initiation and growth energy for delamination. All the materials exhibited significant damage as a result of absorbed impact energy. The damage generated in the bidirectional composites was predominantly delamination and therefore these materials exhibited no significant reduction in post-impact tensile strength. In contrast, the random composites exhibited significant fibre fracture. with concomitant reductions in post-impact tensile strength (>40%). The damage resistance of the bidirectional composites was quantified using impact energy/damage area ratios, but this approach was not applicable to the random composites owing to the difference in the main damage mechanisms.