Non-linear analysis of the curved shapes of unsymmetric laminates accounting for slippage effects

The shape of unsymmetric laminates at room temperature has an out-of-plane deformation after autoclave curing processing. Unsymmetric cross-ply laminates show two stable curvature shapes because of snap-through when the side lengths of laminates are over a critical value. The shapes of the unsymmetric laminates at room temperature are influenced by various environmental factors such as temperature and moisture. Experiments show a significant effect of tool-plate, which cannot be ignored, on the cured shape of an unsymmetric laminate. We developed the simplified higher-order plate theory for laminates with linear transverse shear profile by applying the Rayleigh-Ritz approximation in the solution procedure. For a refined approximation, in-plane strains were expanded to complete fifth order polynomials. The slippage effects resulting from the interaction between the laminates and the tool-plate were considered. A dimensionless slippage coefficient was introduced, which was correlated to the asymptotic curvature value of the model corresponding experimental one was introduced, and the effect of processing parameters were studied. The previous models, which had been applied only to a square plate, were extended to predict curvatures of rectangular plate configurations with various aspect ratios. The slippage coefficient obtained from the square laminates can be used directly without modification to predict curvatures of rectangular plates with various aspect ratios.