Thermal stresses and thermal expansion coefficients of n-layered fiber-reinforced composites

In this work we develop a thermal self-consistent (TSC) model for n-layered fiber-reinforced composites. The fundamental representative volume element is an inclusion made up of a fiber coated by ( n −1) layers encapsulated in an infinite equivalent homogeneous medium. On the basis of the energy equivalence principle we show that the thermal problem under conditions of no external loading can be treated without having to determine the elastic characteristics of the equivalent medium. Thereby, thermal expansion coefficients and microstress distributions inside the layers have been determined according to the proposed semi-analytical and analytical procedures. Both procedures, though different in their implementation, give the same results. The model's performance has been characterized through the successful reproduction of composite thermal expansion and residual stresses calculated from similar studies with different micromechanical models. The proposed model could be useful for (1) analysing the thermal behavior of materials with property gradients, (2) determining thermal expansion coefficients and thermal stresses in n-layer tubing such as gas pipes and (3) studying the effects of interfacial imperfections on thermal behavior.