Enhanced comprehensive performance of bonding interface between CFRP and steel by a novel film adhesive

A novel film adhesive was proposed to bond carbon fiber reinforced polymer (CFRP) laminas to steel substrates, and experimental validations for improved comprehensive bond performances are presented. This film adhesive was shown to possess excellent high-temperature resistance via dynamic mechanical analysis (DMA). A series of CFRP/steel double-lap joints (DLJs) with different bond lengths were experimentally studied, focusing on the failure modes, effective bond length, bond-slip relationship, and bond strength. The results show that the film-adhesive bonded joints fail in the mode of CFRP delamination, which indicates a stronger interfacial bond between the adhesive layer and adherends than the intra-laminar strength of CFRPs. The bonding interface has an effective bond length of approximately 65 mm, beyond which no increase of ultimate load can be achieved with the increase of bond length. The bond-slip relationship of the film-adhesive bonding interface exhibits a trapezoidal (ductile) shape, which is significantly different from the triangular (brittle) shapes for most paste-adhesive interfaces. Superior strength, ductility, and high-temperature resistance of the bonding interfaces in CFRP/steel composites are achieved due to the use of this film adhesive. The proposed study offers an alternative solution to an enhanced comprehensive property of the bonding interface in CFRP/steel composites.