車輛前懸吊系統下擺臂之有限元素分析及結構研究

Abstract

本論文提出一個有限元素模型來研究車輛前懸吊系統中的L型下擺臂結構，並且討論幾何形狀、斷面尺寸及搭接方式對單體上應力集中的影響程度。 從靜破壞實驗可以得到L型下擺臂在車輛前後、側移等4個正負方向的強度值，依實驗數據判定L型下擺臂在車輛前後的正方向時強度最弱而且達不到規範的要求；將規範要求的強度下限值輸入有限元素模型，邊界條件的設定和靜破壞實驗設置一致，並且選擇適當的網格元素及大小，經收斂測試後選定4面體10節點 (CTETRA_10) 為網格元素及6mm為元素切割大小；透過數個幾何形狀、斷面尺寸及搭接方式的修正，在數值模擬分析後可以得到L型下擺臂強度在滿足規範時的結構斷面上的最小尺寸、搭接及幾何形狀。本研究之結果可作為L型下擺臂產品設計在先期工程上的參考資料。

This study proposes a finite element model of L type lower arm in front independent suspension system of automotive. And discuss the static stress in L-type lower arm by geometric form, dimension of cross-section and section layout. We can obtain the strength data of L-type lower arm in four direction of vehicle coordinate by static destructive test. It shows that L-type lower arm can not satisfy the specification in FT direction. Firstly, inputting the required load data to finite element model, then setting the same boundary condition as static destructive test and then choose the correct element type & size. The next step is to solve several modified case to find the minimum dimension of cross-section, the appropriate structural section layout and the correct form shape which can be satisfied the specification. This result of the study can use for preliminary design of L-type lower arm.