Closed form expression for residual stresses and warpage during cure of composite laminates

In this paper, an analytical model is presented to predict the warpage and residual stresses developed during curing of Fibre Metal Laminates (FMLs). The model is generally applicable to other composite materials. The change of stiffness (E modulus) and also the chemical shrinkage of the material during cure is implemented in the model. The developed closed form solution is based on the Classical Laminate Theory (CLT) and an additional term depending on the cure shrinkage. The development of residual stresses can be predicted during cure for both free and constrained (moulded) cure of composite laminates. The input material parameters are determined and used in the model to predict the elastic response of FMLs upon manufacturing. Predictions are compared to simulations with experimental data already obtained for this kind of material. The needed improvements for prediction of the residual stresses and final distortions of FMLs are outlined as the future works.