Free vibration analysis of laminated plate/shell structures based on FSDT with a stabilized nodal-integrated quadrilateral element

This paper reports numerical analyses of free vibration of laminated composite plate/ shell structures of various shapes, span-to-thickness ratios, boundary conditions and lay-up sequences. The method is based on a novel four-node quadrilateral element, namely MISQ20, within the framework of the first-order shear deformation theory (FSDT). The element is built by incorporating a strain smoothing method into the bilinear four-node quadrilateral finite element where the strain smoothing operation is based on mesh-free conforming nodal integration. The bending and membrane stiffness matrices are based on the boundaries of smoothing cells while the shear term is evaluated by 2× 2 Gauss quadrature. Through several numerical examples, the capability, efficiency and simplicity of the element are demonstrated. Convergence studies and comparison with other existing solutions in the literature suggest that the present element is robust, computationally inexpensive and free of locking.