Experimental study on the bond behavior of CFRP-steel interfaces under quasi-static cyclic loading

Abstract

Copious studies have focused on the bond behavior under monotonic loading. However, relative research under quasi-static cyclic loading is still limited. In order to improve the understanding of the bond behavior of CFRP-steel interfaces under quasi-static cyclic loading, an experimental study was conducted in this paper. A series of the CFRP-steel single-shear specimens were manufactured to investigate the effects of bond length, adhesive thickness, adhesive type and loading procedures on the bond behavior of CFRP-steel interfaces. Strains and displacements on the specimen surface were measured by three-dimensional digital image correlation (3D-DIC) technology. The interfacial damage and the threshold load were analysed. The experimental results showed that the loading procedures had no effect on the ultimate loads of specimens with Sikadur-30 (CN), while the ultimate loads of specimens with. Araldite-2015 (CN) under quasi-static cyclic loading were less than those under monotonic loading. The bond-slip relationships under monotonic loading showed bilinear and trilinear shapes for the specimens with adhesives Sikadur-30 (CN) and Araldite-2015 (CN), respectively. The envelope lines of the load-slip and the bond-slip relationship tested under quasi-static cyclic loading could be traced by those under monotonic loading. Relationships between the damage parameter D and the normalized energy dissipation wd/Gf and the normalized slip Si/Sf were established by fitting experimental data. Based on the test results, the threshold loads could be detected for each specimen under the monotonic loading procedure, which was approximately 52.5% and 39.5% of the ultimate load for the specimens with adhesive Sikadur-30 (CN) and Araldite-2015 (CN), respectively.