汽車局部結構強度之有限元素分析

Abstract

基於安全考量，汽車結構強度均需通過測試，為了減少測試次數及縮短開發時程，國際各大車廠均有採用電腦輔助工程(Computer-Aided Engineering，CAE)分析技術從事汽車結構強度設計。 本論文即是建立以CAE進行汽車局部結構強度分析之分析技術。在研究方法上，選定引擎蓋及散熱器支架為研究載具，以有限元素軟體LS-DYNA作為分析工具，進行汽車局部結構CAE分析技術之建立。 對於有限元素模型之建立方法，針對CAD (Computer-Aided Design)圖檔與CAE的轉換問題，網格資料建立時元素大小的考量，各個零件間的組裝方式，以及引擎蓋轉軸機構與引擎蓋卡勾鎖扣機構的模擬模型建立方式提出說明。 模擬分析方面，說明初始穿透問題會造成應力上升的不合理現象，零能模式造成的影響及控制方法，以及如何適當使用質量比例因子來加快模擬運算速度。 最後利用所建立之有限元素模型，進行引擎蓋自由落下撞擊散熱器支架之受力分析。本論文之研究成果可提供進行CAE汽車結構分析時之參考。

The structural strength of automobiles must pass through tests due to safety concern. In order to reduce the time of tests and shorten the developing period, automakers have decided to adopt the CAE (Computer-Aided Engineering) technology to analyze the strength of automobiles. This paper analyzes the strength of automotive sub-structures with the assistance of CAE technology. Using the finite element code, LS-DYNA, the analysis technique for the engine hood and radiator support frame has been built. In regard to the method for building finite element model of automobiles, including the weak convertibility between CAD (Computer-Aided Design) and CAE files, the selection of mesh size, the assembly of parts, the hinge mechanism of engine hoods, and the lock-striker model. This paper also discusses about the influence of initial penetration, usage of hourglass control and mass scaling. Eventually, using the built finite element model, the free fall of the engine hood has been analyzed.