Effects of adhesive property and thickness on the bond performance between carbon fiber reinforced polymer laminate and steel

The bonding between CFRP (Carbon Fiber Reinforced Polymer) laminate and steel plays a key role in the strengthening effects of CFRPs on a steel structure. In this paper, the toughness of the adhesives and the bonding thickness were investigated on the CFRP-steel bond performance using a single lap shear test. The properties of the adhesives, brittle (linear elastic) or tough (nonlinear elastic, lower modulus, higher elongation), led to apparent differences in the ultimate load, stiffness, the shape of the bond-slip curve, and the stress distribution of the CFRP-steel bond. For the tough adhesive, an increase of the bonding thickness from 0.5 mm to 1.5 mm improves the fracture energy but reduces the interface stiffness. On the contrary, for the brittle adhesive, the effects of the bonding thickness are negligible. According to the test and literature results, key parameters of the bond-slip models of the tough adhesive and brittle adhesive in the case of the delamination of CFRP laminate were determined.