Abstract: Bonding joints are easy to connect FRP materials, with uniform stress distribution, good fatigue performance, light weight and other advantages, so they are often used in the lightweight structure of vehicles. The vehicle in the process of service will experience huge challenge such as different coupling temperature, humidity, the adhesive of the durability of the structure, therefore, studying the durability of carbon fiber reinforced composite material connection structures (CFRP-CFRP) for vehicles has important guiding significance for the lightweight of vehicles. The CFRP-CFRP single-lap joints were aged at 60 ℃/95%RH, 60 ℃/100%RH, 60 ℃/3.5%NaCl and 60 ℃/5%NaCl for 240 h, 480 h and 720 h, respectively. Fick’s law was used to simulate the adhesive water absorption process, and compared with the actual water absorption rate. The joint failure load and force-displacement curves were obtained through quasi-static tensile test to explore the mechanical properties of the joint. It was observed that failure load did not increase or decrease uniformly with time increasing, indicating that post-curing (failure load increasing) and environmental erosion (failure load decreasing) were two competing factors with opposite effects. DSC and FTIR test equipment were used to characterize the adhesive before and after aging and its internal failure mechanism was analyzed.

Key words: lightweight, adhesive joint, failure load, post curing, CFRP