This paper presents the large deflection elastic analysis of the hand lay-up composite plates with different extensional and flexural modulus including geometric nonlinearity effects that are taken into account with the von Ka´rma´n large deflection theory of thin plates. Governing equations of the motion are derived by means of the virtual work principle. Then the Galerkin method is applied to reduce the nonlinear coupled differential equations into a nonlinear algebraic equation system. The MATLAB and MATHEMATICA software are used to solve the equation system. Because of the common nonuniformities in hand lay-up fabric laminates such as resin surface layers and unequal layer thickness, the flexural and extensional modulus of such laminated composites are different. By the way, since the bending and in-plane effects are together affect to the nonlinear behavior of a composite laminate, it should give more reliable results when using different flexural and extensional modulus in the analysis. In this study, the results of approximate analysis, ANSYS finite element analysis and experimental study are obtained and compared for a fully-clamped laminated composite plate subjected to a uniform pressure load. The material properties used in the analysis are determined tension and three-point bending tests.
