Modeling the effects of interfacial properties on the temperature dependent tensile strength of fiber reinforced polymer composites

In this study, the stress distribution of fiber axial stress and interfacial shear stress in fiber reinforced polymer (FRP) composites at different temperatures was derived as a function of fiber axial position. The maximum shear stress criterion was extended to be temperature dependent. Based on the extended criterion, the temperature dependent fiber debonding length of FRP composites was predicted, which is indirectly verified by other scholar's experimental study. Then, by introducing the maximum fiber axial stress transferred from the matrix to fiber by their interface including the effect of partial interfacial debonding, we modified the law of mixtures, and finally established the temperature dependent tensile strength model for FRP composites. The model considers the combined effects of temperature, constituents' properties, interfacial properties and residual thermal stress. Reasonable agreement is obtained between the model predictions and available temperature dependent tensile strength of FRP composites. Additionally, the influencing factors analysis for FRP composites is performed in detail. This work provides some important insights on the strength control mechanisms of FRP composites at different temperatures, which are beneficial to the material evaluation, strengthening, and optimization.