Influence of freeze/thaw cycling on the mechanical performance of resistance-welded carbon fibre/polyphenylene sulphide composite joints

Abstract

This study evaluates the effects of freeze/thaw cycles on the mechanical performance and failure mode of resistance-welded carbon fibre/polyphenylene sulphide composite joints. Dry and moisture-saturated joints are subjected to 1000 temperature cycles varying between –40°C and 82°C. A silane coating is applied on the stainless steel mesh heating element to improve its adhesion with the polyphenylene sulphide polymer. Results show the limited impact that freeze/thaw cycles have on the lap shear strength of joints welded without any coating on the heating element. The silane coating improves the lap shear strength by 32% when no freeze/thaw cycles are applied to the joints. This improvement of 32% reduces when joints are subjected to freeze/thaw cycles but the mechanical performance remains superior to that of joints welded using uncoated heating element. Fracture surfaces show that fibre/matrix and stainless steel/matrix interfaces are both affected by the environmental conditions although it does not translate into lower lap shear strength.