Understanding residual stresses in thick polymer composite laminates

The process conditions of thick thermoset matrix composite laminates are complicated by adverse effects involving large out-of-plane temperature gradients and internal heat generation. This chapter introduces the methods to analyze the transient heat transfer and the curing process of thick laminates, by combining the finite element method with thermochemical and self-consistent field micromechanical models. The methods of measurement of residual stresses in thick laminates are introduced. Some experimental results are demonstrated. The techniques discussed are not only applicable to the study of residual thermal stresses but also to stresses induced by environmentally induced internal stresses caused by moisture, temperature gradient, solvents, etc.