Strength Analysis And Investigation About Laminated Structures Based On Numerical Method

Unique advantages of the laminated composite structure make it more and more popular in energy industries and other areas. Accurate predication and evaluation of the deformation and stress of the structure when it is under mechanical or thermal load is significant for safety and economy of the integral unit and also provide basis for optimization design of the structure.Due to the special laminated structure, it is very promising to simplify the complicated three-dimensional problems to two-dimensional one. It is well-known that the plate and shell theories for laminated composite plates and shells have done very well to simplify the three-dimensional solid structures to two–dimensional plates and shells, but many assumptions have been introduced into those theories make them not feasible for other special laminated structures. Such as the First Wall of the Shield Blanket Module at the International Thermonuclear Experimental Reactor (ITER), its structures has many differences from the conventional laminated composite plates and shells, so recently, it has to use experimental method or three-dimensional numerical simulation for researching and investigation of the deformation and stress of this kind of structure. So the ultimate objective of this research is to find a new FE model to solving those problems based on Nonlinear High-order Core Theory.The Nonlinear High-order Core Theory based on the sandwich composite plate takes into account the compressibility of the soft core of the three-layered structure and thus, the transverse displacement in the core varies as fourth order functions of the transverse coordinate, the in-plane displacements in the core are fifth order function of the transverse coordinate. This representation allows an accurate modeling of wide ranges of core types and aspect ratios of sandwich plate.In this thesis, firstly, three-dimensional elastic finite element analysis for sandwich plate of different aspect ratios and different loadcase is presented. And then, a finite elements model based on Nonlinear High-order Core Theory for elastic composite sandwich plate is developed. This new finite elements model simplifies the three-dimensional problem to a two-dimensional problem and the feasibility and accuracy of this finite elements model is verified by several examples and the three-dimensional elastic solutions. At last, three-dimensional elastic analysis for the laminated structure of ITER first wall is studied and the results will be the reference for further study of the extend application of the Nonlinear High-order Core Theory for other laminated structures.