The fracture behaviour of continuous SiC and carbon fibre al- matrix composites under mode ii loading conditions

Abstract EN

The fracture behaviour and in-plane shear properties of unidirectional continuous SiC and Carbon fibre- A1 matrix composites subjected to mode II loading conditions (direct shear mode) has been studied.

A unique pure shear fracture test is devised to evaluate the in-plane shearing mode toughness of such composites based on fracture tests of shear specimens with pre-cracked edge-crack configuration specimens.

The little variation in mode II toughness values with different crack lengths for both reinforced and unreinforced matrix materials indicate the suitability of the devised mode II specimens and the shear fracture tests.

The results obtained for in-plane shear properties show that the shear strength of SiC-Al(1050) and Carbon-Al(356) composites mode II1, where low fibre-matrix interfacial strength exists, is slightly higher than that of SiC-Al(354) composite mode II, which seems to have a profound effect on the shear properties.

The mode II stress intensity factor, K II, is higher than the opening mode I fracture toughness of the reinforced and unreinforced composite materials, owing to the different fracture mechanisms involved,