Effect of sealing treatment on mechanical properties of CFRP-Aluminum alloy single lap joints

To comprehensively investigate the effect of sealing treatment on mechanical properties of CFRP-aluminum alloy single lap joints (SLJs), three typical hygrothermal environments were selected. The failure strength and failure mode of the joints before and after the sealing treatment and hygrothermal aging were analyzed. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analyses were used to explain the aging behavior of the adhesive and CFRP . The influence degree of hygrothermal environment on the performance of the SLJs was obtained by ANOVA. The results demonstrate that the failure strength of the SLJs decreases with the aging time, but the rate of decline of the joints strength after the sealing treatment is considerably lower. The mechanical behavior of the SLJs mainly depends on the ambient temperature and humidity. 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. In contrast, although the failure surface of the SLJs after seal aging will also have aging phenomena such as interface failure and fiber tear, their occurrence time and aging degree are greatly weakened.