Natural frequencies of sandwich plates with FGM core via variable-kinematic 2-D Ritz models

This paper deals with the formulation of advanced two-dimensional Ritz-based models for accurate prediction of natural frequencies of thin and thick sandwich plates with core made of functionally graded material (FGM). The formulation is rather general due to its invariant properties with respect to the underlying plate kinematic theory and the admissible set of Ritz functions. Convergence and accuracy of the method are investigated in this work using an entire family of higher-order layerwise and equivalent single-layer theories, whose corresponding displacement variables are approximated by series of Chebyshev polynomials multiplied by appropriate boundary functions. Results are presented for rectangular sandwich FGM plates with various thickness-to-length ratios and combinations of clamped, free and simply-supported edges.