系統化複材三明治車體結構設計及最佳化方法

Abstract

本研究針對高比強度及剛性之複合材料三明治車體結構，結合構成材料選擇､基本尺寸解析估算､實驗測試､及最重要的高效率自動化最佳化設計､局部套筒設計，建構一涵蓋完整系統化流程，目標在於提供複雜複材車體結構清楚完整之設計參考。 本論文首先比較常用複合材料面､心材比剛性､強度等特性，提供設計選擇參考，以所選擇材料，對於結構體進行初步梁､板解析計算､實驗及基本最佳化方法整理，續針對車體結構所需嚴苛剛性及強度需求，針對三明治結構特性提出演化式三明治結構最佳化方法及等效殼元素等工具，以遠高於傳統方法之效率最佳化材料參數組合。最後針對三明治結構弱點-應力集中處進行細部設計分析，建構完整設計考量。本研究並以兩個設計完成實例：台大機械第三代太陽能車及第一代燃料電池複合動力車展示所開發設計方法之流程及成果。 根據本論文之系統化設計及最佳化流程，能夠根據設計者需求，以最短時間完成一最高比剛性或強度之車體結構，特別是對於日益苛求重量之未來節能車輛或高性能跑車，達到遠低於傳統金屬結構重量之理想。

This research focuses on ultra-high specific stiffness and strength composites sandwich car structures. The topics include material selection, analytical evaluation, experiments, highly efficient and automatic optimization tools, and detailed insert design. It aims to construct complete and systematic design procedures to deal with complicated composites structures. It firstly compares practical face and core materials for selection references, and summarizes experiments and analytical optimization methods for simple beams or plates. The whole body structure optimization is then carried out with a novel algorithm-ESSO (Evolutionary Sandwich Structural Optimization) and an equivalent shell element. The proposed optimization method can efficiently find out best material combinations to fulfill tough stiffness and strength requirements for various driving conditions. Besides, it developes detailed design methods for sandwich structure weakest points, where concentrated loads applied. Two successful design examples-the third generation solar car and the first generation fuel-cells hybrid car of Mechanical Engineering Department, National Taiwan University demonstrate efficiency and accuracy of the proposed design and optimization procedures. In conclusion, this research provides an effective way for designers to design a highly efficient green car or a high-performance sports car that expects an extra-low weight structure.