Temperature-dependent strength modeling of fiber-reinforced composites considering critical properties evolution

Abstract

As the aerospace field rapidly develops, the application of fiber reinforced polymer (FRP) composites in extreme environments, particularly at elevated temperatures, has become increasingly widespread. The theoretical study on the temperature-dependent tensile strength (TDTS) of FRP composites has always been a significant research issue, which closely concerns the service safety of FRP composites in different temperature environment. Herein, the distribution expressions of temperature-dependent fiber axial stress as a function of axial position was first derived in the bonding and debonding zone of FRP composites. Then, based on the Force-Heat Equivalence Energy Density (FHEED) principle and introducing the effect of a wide range of fiber content, we proposed a novel TDTS model of FRP composites with physically-based theoretical method. The presented model can quantify the combined influences of temperature, fiber/matrix properties, residual thermal stress, and especially the critical properties evolution including the interfacial properties and fiber agglomeration. The TDTS of FRP composites with different interfacial properties and fiber contents can be readily predicted by the model, and attain a reasonable agreement with the available experiments. Additionally, the critical parameters affecting the mechanical properties and the evolution with temperature were analyzed, which can effectively provide the beneficial insights for composites strengthening. The work provides a novel tensile strength theoretical model of FRP composites at different temperatures and fiber contents, and further deepens the understanding of the mechanical properties degradation and composites improvement.