Effects of loading rates on mechanical property and failure behavior of single-lap adhesive joints with carbon fiber reinforced plastics and aluminum alloys

Abstract

In this paper, the effects of loading rate on mechanical property and failure mode of carbon fiber reinforced plastic (CFRP) composite and aluminum alloy (Al) single-lap adhesive joints were investigated. Four loading rates (2 mm/min, 4 m/s, 8 m/s, and 12 m/s) were chosen to carry out the shear tests. Digital image correlation (DIC) technique was used to analyze the strain evolution of the joints. Results showed that the shear strength increased with the increase of loading rate. When the loading rate increased from 2 mm/min to 12 m/s, the average shear strength of the joint increased from 19.3 to 29.2 MPa. The load-displacement curves under dynamic loading had two peaks, which is mainly caused by local failure and progressive failure of the joints. There were stress concentrations at both ends of the bonding area, which caused cohesive failure and fiber-tear failure. At both ends of the bonding area, the failure mode was mainly cohesive failure of the adhesive, whereas the failure mode in the middle of the bonding area was mainly resin matrix failure of the CFRP. Wherein the peak loads had a certain correspondence with failure modes and failure regions.