The effect of adhesive thickness on interlaminar fracture toughness of interleaved cfrp specimens

Abstract The investigation concentrated on the adhesive size effect on interlaminar fracture toughness ( ift ) of interleaved cfrp specimens. In tests an artificial interlaminar edge crack was forced to propagate under two modes: separation (Mode I) and shear (Mode II). Two types of adhesive were used and adhesive thickness ranged from 0.04 mm–1.1 mm. Results indicated that ift increased with adhesive thickness up to 10-fold in the case of Mode I and up to 7-fold in the case of Mode II compared with the ift of non-interleaved counterparts. The toughening effect was more pronounced at the low range of thickness and tended to decrease in the case of thick layers. In Mode II ( enf test), ift was found to decrease above an adhesive thickness of 0.7 mm. It was concluded that optimum adhesive thickness for improved ift is in the range of 0.1 - 0.7 mm.