Mechanical performance of resistance-welded thermoplastic composite double lap shear specimens

An investigation of resistance welding of thermoplastic composite double lap shear specimens is presented. Double lap shear specimens consisting of unidirectional 16-ply PEKK/carbon fibre (PEKK/CF) composite were resistance-welded using a stainless steel mesh heating element. The objective of this work was to study the mechanical performance of the double lap shear resistance-welded joints and to compare it with the single lap shear resistance-welded joints. The welded specimens were analyzed using static and fatigue lap shear tests, and optical microscopy. Lap shear strength of 49 MPa was obtained with a PEKK/CF double lap shear joint. Indefinite fatigue life was obtained with a stress level of 30% of that strength. Fracture surface observation revealed an interlaminar mode of failure with tearing of both laminate and heating element. Results from the double lap shear and the single lap shear specimens were compared and no significance difference was noted for the static tests, while a slightly better fatigue performance under low stresses was observed for double-lap-shear specimens.Peer reviewed: YesNRC publication: Ye