Failure analysis of mechanically fastened glass fiber/epoxy composite joints under thermal effects

An experimental failure analysis has been carried out to determine the effects of thermal condition and tightening torque on the failure load and failure behavior of single lap double serial fastener glass fiber/epoxy composite joints. 40, 50, 60, 70, and 80 °C temperatures were exposed to the specimens during tensile tests. It was seen that, the load-carrying capacity of the joint is decreased gradually by increasing temperature level. In proportion to the room temperature, the maximum decrease of failure loads occurs at 70 °C and 80 °C with the rate of nearly 55% and 70% respectively, because of the heat damage to the resin matrix. Besides thermal effects, 0 and 6 Nm tightening torques were applied to observe how clamping forces affect the joint strength. The results proved that, tightening torque is effective not only at room temperature, but also at elevated temperatures and contributes to the joint strength.