Thermo-elastic constants of cracked symmetric laminates: A refined variational approach

The present research work is aimed at predicting degradation of laminate stiffness and laminate thermal expansion coefficients (TEC) as a function of crack density for general symmetric laminates containing intralaminar matrix cracks. Therefore, an exact methodology is developed based on Levin׳s theorem to evaluate the effective thermal expansion coefficients of cracked laminates. Then, an admissible stress field, which satisfies equilibrium equations and all the boundary and continuity conditions, has been considered in conjunction with the principle of minimum complementary energy and a ply refinement technique in order to exactly predict degradation of all thermo-elastic constants of cracked symmetric laminates. Results derived from the developed method for thermo-elastic properties of the cracked laminates showed an excellent agreement with finite element and experimental results available in the literature. Moreover, a comparison has been made between the capability and accuracy of various models in predicting thermo-elastic constants of cracked laminates. It has been shown that the results obtained from the current approach are more accurate and also more consistent with finite element results compared to those obtained from shear-lag approach.