Friction stir welding of lapped low-melt polyaryletherketone carbon fiber reinforced thermoplastic laminate

Abstract

Carbon fiber reinforced thermoplastics (CFRTP) have increasing use in aerospace structures due to improved process-ability and weldability. In this study, lap joints between carbon fiber reinforced low-meltpolyaryletherketone (LMPAEK) are formed by friction stir welding (FSW). This study presents novelty by applying FSW to continuous carbon fiber composites in woven laminate form. FSW disrupts the fibers in the weld zone and distributes fragments as small as several microns in length. Thermal analysis shows that the weld zones degrade at 40°C cooler temperatures than the base laminate material due to enhanced polymer mobility surrounding the disrupted carbon fibers. Though optimized joints have regions of over 9% porosity, tensile strengths of up to 73.8 MPa retains up to 50% joint efficiency of a comparable short carbon fiber reinforced composite. CFRTP also requires lower processing forces during FSW than metals, and the power consumption of 67 W during the traverse period for strength optimized welds retains energy efficient characteristics.