EXPERIMENTAL ASSESMENT OF INFRARED WELDED BONDS USING LAPSHEAR, DOUBLE CANTILEVER BEAM AND END NOTCH FLEXURE TESTS FOR A CARBON FABRIC REINFORCED THERMOPLASTIC

High performance composites, such as carbon-fibre reinforced plastics (CFRP), are increasingly being used in high engineering industries. Their wide acceptance introduces an issue regarding the bonding of these materials and their mechanical behaviour. As this reinforced thermoplastic is not easily bonded with adhesives due to the chemical inertness, the fusion bonding process could be used to make a structural bond. In this paper, the interlaminar fracture behaviour of infrared welded bonds was investigated based on experimental analysis. The material used, is a 5-harness satin-weave (5HS) carbon fabric-reinforced polyphenylene sulphide (PPS). Laminates were welded using infrared light and a delamination was introduced by a Kapton film. Welding parameters were first optimized using lapshear tests, then mode I and mode II tests were conducted to determine the fracture toughness behaviour of the welded bonds. Tests under mode I loading were carried out using double cantilever beam (DCB) specimens whereas for mode II loading, three-point end notched flexure (ENF) specimens were considered. Crack growth under mode I and mode II loading conditions was observed to be unstable resulting in a sawtooth like load-displacement response, but nevertheless, values for the fracture toughness were derived.