Effect of sealing treatment on the resistance of lap joints to hygrothermal aging

ABSTRACT

To investigate the influence of sealing treatment on the resistance of lap joints to hygrothermal environment, Al-CFRP single lap joints (SLJ) and Al-CFRP-Al double lap joints (DLJ) were selected as the research objects, and hygrothermal-cyclic aging test was carried out based on the vehicle service environment. The failure strength and failure mode of the joints before and after the sealing treatment and hygrothermal aging were analyzed. Fourier transform infrared (FTIR), thermogravimetric (TG), and scanning electron microscopy (SEM) analyses were used to explain the aging behavior of the adhesive and CFRP. The failure strength of the lap joints decreases with the aging time, but the rate of decline of the joints strength after the sealing treatment is considerably lower. The failure mode of the lap joints is cohesive failure before aging. At the beginning of the aging process, interface failure appears at the edge of the failure surface of the joints and gradually leads to the fiber tearing. Moreover, due to the diffusion mechanism of water molecules, the aging behavior at the edge and the center of the interface is different. When the joints is sealed, the aging behavior caused by aging time and aging path will be considerably weakened.

KEYWORDS:

• Carbon fiber reinforced polymer composites
• epoxy adhesive
• sealing treatment
• hygrothermal aging
• lap joints

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [51775230]; Graduate innovation research program of Jilin University [101832020CX124];National Science Foundation of China [51775230];Graduate innovation research program of Jilin University [101832020CX124];