Pre-curing and molding forming of 6061/CFRP structural U-shaped parts under different molding pressure

Abstract

Metal and carbon fiber reinforced polymers (CFRP) laminates can be used to manufacture lightweight and high-strength automotive parts, which play an important role in the lightweight of the body. In this paper, an integrated pre-curing and molding forming process of 6061-T6 aluminum alloy and CFRP was proposed. The influence of molding pressure on the forming accuracy and mechanical properties of the formed parts was systematically investigated through experimental methods. The mechanical properties of the CFRP/Al hybrid composite parts were examined by flexural test, and the macroscopic morphology, metallographic structure and microscopic structure of the formed parts were observed by optical microscope and scanning electron microscope, respectively. The optical coordinate measuring instrument was used to measure the spring-back of the formed parts. The results demonstrated that compared to a single 6061 aluminum alloy, the flexural strength of CFRP/Al hybrid composites increased by 158.64%, 139.79%, and 88.68% under molding pressures of 4 MPa, 8 MPa, and 16 MPa, respectively. Similarly, energy absorption improved by 96.38%, 57.11%, and 27.35% under these respective pressures. As the molding pressure increased, it will lead to excessive extrusion of resin during the prepreg forming process, increase the thinning rate of parts, and reduce the flexural strength and energy absorption properties. However, the increase of molding pressure will reduce the springback of formed parts and improve the accuracy of the shape surface of parts. Considering both the mechanical properties and geometric accuracy, a molding pressure of 4 MPa was determined to be optimal for this study.