Structural Optimization Of Truss-Core Sandwich Plates With Multiple Objectives Based On Method Of Centers

Periodic truss-core sandwich plates have recently been investigated for their lightweight and multi-functional characteristics such as ultra-light, high compring stiff and strength, shock resistance, thermal resistance, sound insulation and electromagnetic shielding. Recent developments in the manufacturing techniques appear to heighten the interest in such plates, and these kinds of sandwich plates are considered as the most perspective and novel ultra-light materials combined with specific strength and multi-functions.To exploit the multi-funcation of periodic truss-core sandwich plates, the macroscopic effective stiffness and strength, frequency and collapse of solid faces and truss core plates are studied. The multi-objectives optimization models of truss-core plates are founded. A method of centers is proposed and a general programme is developed to solve the multi-objective problem, the Pareto sets are given out. Some numerical examples justified the feasibility of the arithmetic.This thesis includes five chapters, as briefly reviewed follow:In chapter 1, background of this paper and the review of literatures are introduced. The structure of the periodic truss-core sandwich plates is briefly introduced. The emphasis is put on introducing some representative jobs in this field in the foreign countries and domestic research, including, theoretical methods, static and dynamic experiment, multi-functional characteristic and the optimization of the truss-core plates.And then the necessary for multi-objectives research is reviewed, this paper is proposed based on the above.In chapter 2, some necessary mathematical tools required in this paper are presented. First, some general multi-objectives optimization problems and solutions are presented.And then, method of centers is investigated based on maximum entropy method and aggregate function approach.In chapter 3, mechanical .properties of periodic truss core sandwich plates are studied. First, the manufacturing and structural characteristic of the truss-core sandwich plates are presented.Then, attention is given to mechanical performance.The stiffness, strength and dynamic performance of the plates are presented. All of these parameters agree well with ANSYS finite elements analysis.In chapter 4, method of centers for multi-functional optimization is applied to the structural optimization of truss core sandwich plates. Optimization model for 3-benging truss-core sandwich plate is established based on studies in Chapter 3, and then solved by method of centers. High efficiency of method of centers is indicated through the comparison with optimization of literature. Multi-objectives optimization models for the truss-core sandwich plates of this loading case are also established. Method of centers is utilized to solve these multi-objectives optimization, and the Pareto Sets are given out. The research results show that optimization with single objective or multiple objectives are unified by method of centers,which facilitates to adapt this algorithm to the existing FEM analysis and optimization programs.The last chapter gives out a summary of the dissertation and some possible extensions of the present work.This thesis is supported by the National Natural Science Foundation of China under Grant 10332010, 10572031.