Temperature-Dependent Interfacial Debonding and Frictional Behavior of Fiber-Reinforced Polymer Composites

Abstract

As fiber-reinforced polymer matrix composites are often cured from stress-free high temperature, when subjected to ambient temperature, both the mismatch of the coefficient of linear thermal expansion between the fiber and the matrix and the dependence of material properties on temperature will influence the interfacial behavior. Thus, it is necessary to provide an insight into the mechanism of temperature effects on the thermomechanical properties and behaviors along the interface. In this work, we conducted microbond tests of the glass fiber–epoxy material system at controlled testing temperature (Tt). A modified interface model is formulated and implemented to study the interfacial decohesion and frictional sliding behavior of microbond tests at different Tt. With proper cohesive parameters obtained, the model can predict temperature-dependent interfacial behaviors in fiber-reinforced composites. Both the slope of the peak force as well as the measured force at the stage of frictional sliding decrease with Tt in a wide range of the length of microdroplet-embedded fiber (le). The interfacial shear strength (IFSS) keeps almost constant at Tt ≤ 40 °C and decreases with le when temperature is above 40 °C. The average frictional stress (τfAverage) along the interface increases with le when temperature is below 80 °C but is almost constant when temperature is above or equal to 80 °C. Overall, in the same range of le, τfAverage is greater when Tt is at low temperature.