Post Buckling Behavior Analysis Of Composite Laminated Plates And Shells Structures

Composite laminated thin-walled structures are widely used in aerospace and aeronautic structures due to weight-light, their high specific strength, high specific stiffness, fatigue resistance and flexibility in design. In fact, laminated plates and shell under buckling do not fail, and these structures can still have a reasonable load-carrying capacity, which is generally named post-buckling strength. For the modern aircrafts and space probe , taking full advantages of post-buckling load-carrying capacity of laminated structures is both economical and realistic to increase the resistance buckling failure, reduce the overall weight and optimize laminated structures design.Resorting to the Von-Karman large deflection theory and considering the effects of geometrically nonlinear behavior, the nonlinear stability governing equations of laminated thin plates and shallow shells of arbitrary stacking sequence under in-plane compressive loading was established by using variational approach and the minimum potential energy principle in this paper. Adoption the method of Weighted Residuals, the governing nonlinear partial differential equations were converted into a set of nonlinear algebraic equations, which were solved by using of load increment and Newton iteration method. The corresponding program was developed. Post-buckled equilibrium paths were scouted for laminated plates with and without initial geometric imperfections.The validity and effectiveness of the theory and method presented in this paper are demonstrated by comparing with the solutions obtained by the other existent references. It has been demonstrated from observation that a fairly good agreement is achieved. The post-buckling behavior was investigated with this program, the effects of various factors on the critical buckling loads and post-buckling behavior of simply supported laminated plates are detailedly analyzed, which include initial deflection, material properties, ply angles, aspect ration, thickness, number of layers, and stacking sequence.Reinforce structures with stiffeners is another effective method to improve load carrying capacities. These structures are less subjected to uniform load and the edges of these structures were mostly under concentrated loads and distributed loads, which are usually acting on oneend, both ends and middle position. Influence of different kinds of loading on the critical buckling loads of different aspect ratio structures with and without stiffeners. Finally, the effects of number, height, thickness and ply angles of stiffened on the critical buckling loads are respectively discussed in detail.