Experimental and Theoretical Characterization on the Temperature Dependent Tensile Strength of <scp>FRP</scp> Composites Considering Interfacial Properties and Fiber Agglomeration

ABSTRACT Fiber reinforced polymer (FRP) composites have emerged as critical materials in the aerospace field. In the application, the characterization of the mechanical properties of composites with different fiber contents at different temperatures has long constituted a significant research area. This study conducted a combined experimental and theoretical approach to investigate the effects of fiber content and temperature on the mechanical properties of FRP composites. Firstly, this study examined the mechanical responses of tensile specimens of composites; it was found that the degree of nonlinearity in mechanical behavior increases with higher fiber content, while both tensile strength and failure strain initially rise and then decline as fiber content. Furthermore, the tensile tests at varying temperatures revealed a significant decrease in tensile strength with increasing temperature. Finally, based on the Force‐Heat Equivalence Energy Density Principle (FHEEDP), this work established a temperature dependent tensile strength (TDTS) model for FRP composites. It considers the influences of temperature, fiber/matrix properties, and residual thermal stresses, particularly the interfacial performance and fiber agglomeration. The model employs a physically‐based theoretical method, enabling prediction of the TDTS of FRP composites. This study provides the theoretical basis for predicting their strength performance and reliability evaluation of FRP composites under service conditions.