Analysis of crack behavior in an Epoxy-fiber composite under thermal and thermo-mechanical loading

The mechanical behavior of composites depends on commissioning stresses and environmental conditions of use. They are usually subjected to complex mechanical loadings. Their endurance and their lifespan require knowledge of their behavior under such solicitations. The fiber-matrix junction is usually made at high temperatures. When cooling this junction to ambient temperature, internal stresses arise from the difference in the thermal expansion coefficients between the matrix and the fibers. The combination of these stresses with those of commissioning determines the reliability and the performance of the composite. In this study, a numerical model has been developed to analyze the effect of this combination on the lifetime in terms of stress intensity factors variation in modes I and II at the heads of an initially interfacial crack. An epoxy matrix reinforced with fibers. This variation is analyzed according to the orientation of the crack, the intensity of commissioning stresses, the elaboration temperature of the composite, of the combination of stresses of commissioning-internal stresses, the nature of the fibers and their volume fraction.