車輛結構動態與疲勞分析

Vehicle Structural Dynamic Simulation and Fatigue Prediction

姜承甫(Cheng-Fu Chiang)

指導教授 ： 陳嘉勳

國立臺北科技大學/機電學院/車輛工程系所/碩士(2013年)

https://doi.org/10.6841/NTUT.2013.00280

摘要

本研究以全地形車(ATV)車架模型做電腦輔助分析，主要目的是模擬車輛零部件行駛於隨機不平坦的道路，造成隨時間變化的動態應力大小，進而計算出零部件的疲勞壽命長度。本論文先以SolidWorks建模車架圖檔，再以HyperMesh作為前處理器，來完成車架模型的網格劃分，再經由Nastran模態分析產生柔性體中性檔，並以Adams/View軟體為動態模擬平台，匯入模態中性檔取代剛體。透過動態行駛的路面回授應力測試，求出車架上承受最大應力節點每個時間的應力大小，然後將各模態的應力時間歷程匯入MSC Fatigue做疲勞分析，求解零件的疲勞壽命。最後依照分析結果來預測車架容易破壞的位置，並假設各種路面的比例得到車架的壽命為25833.6小時，如車輛每天行駛於此道路八小時，則有8.847年的使用壽命。運用柔性體的動態模擬技術，較使用剛體模型的計算，更能切確地描述實際物體因彈性變形的運動情況。相對於有限元素法的網格計算方式，可大量減少矩陣方程式自由度，節省軟體計算時間，與計算資料的檔案大小。使用電腦模擬的方式代替實車測試，可減少開發測試成本，加速耐久性測試時間，獲得產品壽命預測，在產品量產前的設計階段上給予參考與改善，完成從頭到尾一連貫的耐久性分析流程。

關鍵字

動態模擬 ； 柔性體 ； 疲勞分析

並列摘要

In this study, a flexible body dynamic model of an all-terrain vehicle (ATV) is analyzed to recover dynamic stresses while the ATV travels on random bumpy roads, and the fatigue life of components is predicted. The ATV geometric model is built with SolidWorks first. Then, the model is meshed with HyperMesh, and analyzed with Nastran to provide the flexible body neutral files. These neutral files are imported to dynamic simulation platform (Adams / View software) for flexible body dynamic simulation. During the simulation, the stress time history of ATV structure is recovered, and imported to MSC Fatigue for life prediction. Finally, the hot sports of the ATV frame are located, and the frame life for combined road conditions is predicted, which is 25833.6 hours. If the usage of vehicle is eight hours per day, the total vehicle frame life is 8.847 years.
It is more accurate to describe the reaction force and deformation due to the dynamic motion by using flexible body dynamics than the rigid body dynamics. The procedure developed in this research can greatly reduce the degree of freedom of the dynamic equations, software calculation time, and size of calculation data. Recommendations could be given in product design stage before the mass production, and this procedure can greatly reduce development and testing costs.

並列關鍵字

dynamic simulation ； flexible body ； Fatigue analysis

參考文獻

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