Experiments and Modeling of Residual Deformations in the Manufacturing of Sandwich and Laminated Composite Structures

Manufacturing residual deformation is the deformation that develops during the curing process of composite structures due to the inherent anisotropic material properties. To quantify these deformations a twofold approach has been taken: the development of an analytical model and an extensive experimental investigation. The model predicts that spring-back in sandwich components is mostly due to mismatch between facesheet inplane and core out-of-plane thermal coefficients of expansion. In solid laminates, an additional contributor is the through-the-thickness chemical shrinkage of the matrix during cure. A complete model of the cure process has been assembled. Through integration and modifications of existing models coupled with experimentation, this model shall be capable of calculating amount of manufacturing residual deformation for a large variety of parts. Results indicate that spring-back angles tend to be less in sandwich parts than in solid laminates.