Abstract
Rods of unidirectional CFRP offer outstanding performance in terms of strength to weight ratio. Their performance is, however, expected to be limited by their resistance to in-service impact threats, especially with regard to compressive loadings. The work reported here has verified that damage is done to unprotected rods at relatively minor impact levels and that a substantial reduction in compressive strength is experienced after impact. Identical rods have been overwound with high modulus aramid fibre under tension to act as a protective layer and subsequently impacted. These rods are much more resistant to impact than the unprotected rods; the best case studied to date being more than three times as strong after impact as the unprotected rods and more than twice as strong when taking the mass of aramid fibre into account. The longitudinal splitting seen in the impacted, unprotected rods has been completely suppressed by the tensioned overwind. This novel approach to reducing the influence of impact on the post-impact properties of composite rods has been validated by these tests.
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