The Application Of ESO In 3D Thermal-Structural Coupled Systems

The topology optimization of thermal-structural coupled system is a common problem in engineering, especially in the fields of aeronautical, Astronautical equipment, electronic parts and micro electro-mechanical system. Basing on the background of Thermal Protection System (TPS) and MEMS designing, this thesis focused on the theoretical and numerical study of 3D continuum topology optimization of thermal-structural coupled system by adopting the Evolutionary Structural Optimization (ESO) method.The research of this dissertation consists of two part. The first part involves the 2D and 3D continuum topology optimization of heat conducting field. The second part is the 3D continuum topology optimization of thermal-structural coupled system. A bi-direction ESO algorithm and a multi-objective ESO algorithm are proposed to strengthen the conventional ESO algorithm. A sensitive number analysis and element selecting scheme is carried out basing on the histogram statistics of the sensitive numbers. Several typical numerical examples is presented to illustrate the effect and efficiency of this research, which is believed to be an important foundation for the theoretical study and software developing in related fields.In Chapter â… , the up-to-date research work on structural and multidisciplinary design optimization is surveyed. And the innovation of this dissertation is summarized.In Chapter â…¡, the finite element method for heat conducting and thermo-elastic analysis is surveyed. Firstly the governing differential formula of heat conduction is introduced and then the finite element method formula of steady heat conduction is implemented by the variation theory. Taking the six-node hexahedron element for example, the detailed FEM formulations are developed.In Chapter â…¢, the conventional 2D ESO method is presented as a reference and foundation of the successive research. The ESO for stress constraints, global stiffness constraint and heat conduction field is discussed in detail respectively. The sensitive number derived from the heat conducting governing equation is the kernel of the heat conducting ESO. Severalexamples are presented to illustrate the method using the program developed under MATLAB, which is the foundation of 3D program.In Chapter â…£, the ESO for 3D heat conducting is introduced in detail. Several innovative method is discussed in detail. The conventional ESO's 3D application is also presented as a control for comparison. Numerical examples are provided.In Chapter â…¥, the optimization problem having a temperature objective and stiffiiess constraint is taken into consideration. The individual element's stain energy density is calculated as a generalized sensitive number for ESO method. By removing the elements that have the least contribution to the structural global stiffness, the efficiency of material in the remaining structure is improved and the weight is reduced.In Chapter â…¥, the contribution of this dissertation is summarized and the future work is suggested.The research of this dissertation is supported by the National Natural Science Foundation of China (No. 10032030 and No. 10402005).