LAP SHEAR STRENGTH Effects of Temperature on the Apparent Lap Shear Strength of Resistance-Welded Carbon Fibre/Thermoplastic Composite Joints

摘要

An experimental study was performed to determine the effects of temperature on the mechanical strength of resistance-welded quasi-isotropic carbon fiber reinforced polyphenylene sulfide (CF/PPS) composite joints. The resistance welding process was used to assemble the joints with a stainless steel mesh heating element (HE). A room temperature lap shear strength (LSS) of 28.47 MPa was obtained. The effects of temperature on the strength was assessed by testing the welded joints at temperatures of 21 degrees C, 62 degrees C, 82 degrees C, 90 degrees C, 118 degrees C and 150 degrees C, corresponding to aerospace standard test temperatures and temperatures near the glass transition of the PPS matrix. The LSS decreased with an increasing temperature with a larger drop in the vicinity of the glass transition temperature (T-g). The fracture surfaces of the joints revealed a failure mode changing from cohesive in the HE to cohesive with the HE remaining on one laminate only between room temperature and 62 degrees C. A third cohesive failure mode between the HE and the matrix was obtained at temperatures higher than T-g. At 118 degrees C, the failure mode was mostly HE disbonding and the mechanical strength was reduced by 49.8%.