Refined Model for Composite Sandwich Laminates of Moderate Thickness Based on the Variational Asymptotic Method

In order to accurately predict the stress/strain distribution along the thickness direction, which is very important to the interface cracking of the composite sandwich laminate of moderate thickness, the small inherent parameter was used to rigidly decouple the original 3D plate into 1D analysis along the thickness direction and 2D nonlinear plate analysis. The 3D energy was approximately extended into a series of 2D energy functionals, in which the leading items were asymptotically corrected to match the original 3D energy as close as possible. Then, a refined model was built up without any field variable assumptions, and converted to the form of Reissner model for engineering applications. The cylindrical bending example of a sandwich plate with four layers shows that the 3D field reconstituted by this theory agrees better with the exact results than those by the first-order shear deformation theory and classical laminated theory; it’s amount of computation can be reduced up to 2~3 orders than 3D finite element method because the variational asymptotic model is an equivalent single-layer plate model, indicating a good tradeoff between the accuracy and efficiency.