LONGITUDINAL SPLITTING IN UNIDIRECTIONAL FIBER-REINFORCED COMPOSITES WITH AN OPEN HOLE

Splitting of unidirectional aramid, glass and carbon fibre-reinforced composites near a circular hole has been studied. Under longitudinal t ensile loading four splits growing in the fibre direction were observe d near the hole. The splits grew with an increase in the applied load. R curves were determined, and an increase in fracture toughness, G(II c),with an increase in split length was observed. The increase in frac ture toughness was explained by the presence of fibres bridging opposi te sides of splits. G(IIc), values at a split length of 50 mm were 4 t o 10 kJ m(-2), roughly IO-times higher than for mode I loading. At a f ixed split length an increase in G(IIc), with an increase in the hole diameter,vas observed. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.