Mechanical Properties of Fiber-Reinforced Polymer (FRP) Composites at Elevated Temperatures

Many materials are gradually softened with increasing temperatures in the fire, which will cause severe damage. As a new fiber-reinforced polymer (FRP) composite, the change in mechanical properties of nanometer montmorillonite composite fiber-reinforced bars or plates at elevated temperatures has not been investigated. To obtain a more comprehensive study of the mechanical properties of FRP composites at high temperatures, experimental research on the nanometer montmorillonite composite fiber material under the tensile rate of 1 mm/min was conducted at target temperatures between 20 °C and 350 °C. Finally, the failure mode of the FRP composites after the tensile test was analyzed. The results demonstrate that the elevated temperatures had a major impact on the residual mechanical properties of fiber-reinforced polymer (FRP) composites when the exposed temperatures exceeded 200 °C. Below 200 °C, the maximum decrease and increase in the fracture load of fiber reinforced polymer (FRP) composites were between −34% and 153% of their initial fracture load. After exposing to temperatures above 200 °C, the surface color of fiber-reinforced polymer (FRP) composites changed from brown to black. When exposed to temperatures between 200 and 300 °C, the ultimate load of fiber-reinforced polymer (FRP) composites significantly increased from 731.01 N to 1650.97 N. Additionally, the stress−strain behavior can be accurately predicted by using the proposed Johnson−Cook constitutive model. The experimental results studied in this research can be applied to both further research and engineering applications when conducting a theoretical simulation of fiber-reinforced polymer (FRP) composites.