Optimization and mechanism of ultrasonic welding process of CF/PEI composite

Abstract

Carbon fiber reinforced polymer composites (CFRP) are widely used in the aerospace field. The efficient bonding technology has an important effect on the manufacturing cost and safety of CFRP components. In this paper, carbon fiber reinforced polyetherimide resin matrix composites (CF/PEI) were welded by ultrasonic welding technology. The effects of ultrasonic welding pressure and welding time on the strength of ultrasonic welded joints were studied by single lap shear strength (LSS) test, and the micro morphology of section was characterized by scanning electron microscope. The experimental data were analyzed by linear fitting, and the time pressure parameters were optimized and the joint strength was predicted by combining BP neural network and genetic algorithm. Finally, the influence mechanism of holding time on joint strength was studied. The results show that when the welding time is 2.5 s and the welding pressure is 0.45 MPa, the maximum LSS is 25.6 MPa, and it is found that the higher welding strength is due to the formation of dense and stable structure on the joint surface. The experimental data are refined by BP neural network. The LSS value simulated by genetic algorithm is 24.8 MPa, and the error between the simulation and the experimental results is only 3%.With the increase of the holding time, the strength of ultrasonic welding joint increases rapidly first and then tends to be stable. When the holding time is 5 s, the molten resin at the welding interface is basically cured completely, and the PEI resin and carbon fiber form a dense structure, and the strength of ultrasonic welding joint is stable.

Keywords

• carbon fiber composites
• ultrasonic welding
• welding pressure
• single lap shear strength
• pressure holding time
• bp neural network