This study proposes a semi-analytical model to investigate the free vibration analysis of laminated composite plates coupled with fluid. This case is representative of certain key components of complex structures used in different industry sectors such as aerospace, nuclear, and naval. The plates are either in air or fully submerged in fluid or floating on its fluid free surface. The mathematical model for composite plates is developed using a combination of the classical finite element method and Sanders’ shell theory. The in-plane and  out-of-plane displacement components are modeled using bilinear polynomials and exponential functions, respectively. The structural mass and stiffness matrices are then determined by exact analytical integration. The velocity potential, Bernoulli’s equation, and the impermeability condition applied to the plate-fluid interface are used to derive an explicit expression for fluid pressure. The product of the fluid pressure and structural shape functions is then analytically integrated over the fluid-structure contact surface to obtain the induced fluid forces in terms of inertial, Coriolis, and centrifugal forces. The eigenvalue problem of coupled fluid-structure system is then solved to determine the natural frequencies and mode shapes of the both isotropic and laminated composite plates. A parametric study is carried out to investigate the effect of physical and geometrical parameters (e.g., material properties, laminas stacking sequence, boundary conditions, and fluid level) on the dynamic response of the coupled system. Structural stability is also discussed for composite plates in presence of flowing fluid. The results are in satisfactory agreement with those of experiments, other theories, and finite element models simulated in ANSYS.

composite plates, dynamics, fluid-structure interaction.