Static Analysis Of Stability And Delamination Growth For Laminated Composite Rectangular Plate With Delamination

As an advance material, laminated composite plates are employed widely in engineering area. But delamination may occur in laminated composite plates under many factors. The existance of delamination and their further growth will drastically reduce the stiffness and residual strength of delaminated plates. Therefore, the damages of the laminated composite plates due to the delamination are always hot issues in the domain of mechanics. A simple supported rectangular plate of the laminated composite material with delamination is investigated. The delamination is considered to be through-width direction, and the plate is divided into four sub-plates by the delamination. Using the plate and shell theory and the mechanics of composite material, problems, such as the elastic buckling, the nonlinear postbuckling and the growth of delamination in the laminated plate, are studied. The effects of the size and the depth of the delamination on the mechanical properties of the laminated plate is investigated. The main research contents are given as follows.The bifurcation buckling of the laminated composite plate is analyzed. Based on the Von-Karman plate theory, the governing equations for each sub-plate are derived. By considering the continuity property of forces and displacements between sub-plates, the continuity conditions are established. Solutions which satisfy boundary conditions and continuity conditions are obtained. A parametric study is conducted to analyze the influence of delamination depth and size on the buckling loads and buckling modes.According to the theory of nonlinear mechanics, governing equations in the postbuckling stage as well as the continuous conditions for the refered plates are derived. Using perturbation approach, the approximate solutions of the governing equations are obtained by introducing a small parameter. In particular, variation of the loads with respect to the deflections as well as the postbuckling deformation modes for the laminated plate under axial compression are plotted. And, the influence of delamination depth and size on the postbuckling characters is discussed.The growth of delamination in laminated plate subject to in-plane load is studied. Using variational principle for varied boundary condition problem, the formula of total energy release rate expressed by stress function and deflection is obtained from Griffith criterion. In addition, the influence of parameters, such as the delamination size and depth, on the energy release rate is discussed in detail.