Experimental Study of the Effect of Temperature on the Circumferential Bending Performance of GFRP Pipes

Glass Fiber Reinforced Plastic (GFRP) pipes are widely used as polymer-based composite pipes in various engineering fields where the temperature influences their performance. This paper investigated the circumferential bending properties of GFRP pipes with different continuous fiber contents at 30 °C, 50 °C and 70 °C. GFRP pipes are classified into three types according to their component content: type I, type II and type III. The results show that the bending performance of GFRP pipes tends to decrease with increasing temperature, with the retention of circumferential stiffness being 80–85% and the retention of bending strength and damage displacement being about 25–40% from 30 °C to 70 °C. The rate of decay of ring stiffness, bending strength and damage displacement is significantly higher from 30 °C to 50 °C than from 50 °C to 70 °C. Both temperature and continuous fiber content greatly influenced the damage pattern. At 30 °C, delamination damage occurred at the top and bottom of the Type I GFRP pipe before fracture damage happened at the left and right ends and fracture damage occurred at both the left and right ends of Type II and Type III GFRP pipes. Delamination damage happened at the upper and lower ends of the GFRP pipes at 50 °C and 70 °C. In addition, the paper analyses the mechanisms of the associated effects.