“…For general boundary conditions, however, the analytical solution cannot be obtained due to the complexities introduced by the satisfaction of free edges and free corner boundary conditions. So, various approximate or numerical methods such as the Ritz method [1,7,8], the differential quadrature method (DQM) [9][10][11][12], the method of superposition [13], the extended Kantorovich approach [14,15], the spectral finite element method [16], the finite element method with basic displacement functions [17], the finite element method with isogeometric analysis [18], the mesh-free method [19], BEM-based meshless method [20], the moving least squares differential quadrature method [21], semi-analytic differential quadrature method [22], the projection equation approach [23], the finite difference method [24], the spectral element method [25], the discrete singular convolution method [26][27][28], the radial basis function-based DQM [29,30], the weak-form DQM [31], and the strong-form finite element method [32][33][34] have been developed to study the behavior of rectangular plates with general boundary conditions. Among the approximate analytical methods utilized for addressing the present problem, the Ritz method is one the most convenient methods to obtain the natural frequencies of rectangular plates [1,[35][36][37].…”