- 學位論文
電動輔助自行車結構之有限元素法分析
Finite element analyses on the structure of electric aided bicycle
摘要
本研究主要目的為利用有限元素軟體分析電動輔助自行車車體結構，並對車體設計提出可行之建議。本文總共分析二種車型，分為一般式車架及摺疊式車架兩大類。一開始，參照廠商提供之實體模型，利用 Pro-E 及 Solidworks電腦繪圖軟體製作電動輔助自行車車體結構電腦模型，然後利用有限元素分析軟體ANSYS及LS-DYNA模擬求解。模型依照各種不同的邊界及負載條件進行車體靜態、模態、動態及撞擊等分析。最後，利用模擬之結果進行車體結構分析並提出設計建議。 本研究建立了一套完整的電動輔助自行車結構分析方法，包含靜態、模態、動態、撞擊等分析。並利用模擬之結果訂出功率頻譜密度PSD (Power spectral density) 及車架受傷指數FIC (Frame Injury Criterion)，分別作為車架舒適程度及車架受傷程度之指標。靜態及撞擊分析之結果均顯示最大應力值、最大位移及最大之FIC值出現於固定馬達之接管，且從模態分析發現車體結構經過電池與馬達加重之後，其自然頻率有顯著的降低，使得無刷馬達之運轉頻率有可能與車體產生共振效應。動態模擬結果顯示較高車速行駛會使PSD值增加及舒適度降低，且因後輪及座位於低頻處之PSD值最大，對低速行駛之舒適度具嚴重威脅。模擬結果發現最小PSD值發生在前避震器接近把手的位置，此顯示避震器對增加舒適度有明顯的效果。
並列摘要
The goals of this research are to analyze the frame structure of electric aided bicycle by using the finite element analysis software and to make the feasible suggestion about the structural design. This article analyzes two kinds of bicycle types, means the foldaway frame and the common frame. From the beginning, to refer to the model provided by manufacturer and helps by Pro-E and the Solidwork, the computer models of electric aided bicycle were demostrated. Then, finite element analysis software ANSYS and the LS-DYNA were introduced to obtain the results of simulation, and analysis of static, modal, dynamic and impact were conducted in according to different boundary conditions and load types. Finally, with the help of simulation results, the suggestions of the structural design about electric aided bicycle were proposed. This research provides integrated method of structural analysis of electric aided bicycle, means the analysis of static, modal, dynamic and impact. By using the simulation results, the power spectral density (PSD) and the frame injured criteria (FIC) are defined to describe the comfort index and frame injured level of the frame of bicycle. Results of static and the impact analysis show that the largest value of stress, displacement and FIC occurs in the connect pipe which fixed motor. From the modal analysis, the natural frequencies of bicycle structure which are aggravated the battery and the motor mass, are significantly reduced, and results to the resonating effect between the frame of bicycle and the non-brush motor. The dynamic simulate results show that the high speed travel can make the PSD value to increase. The PSD around the lower frequencies near the rear wheel and the seat have the largest values, this tends to have serious threat to comfort level when the travel speed of bicycle is low. Oreover, the smallest PSD value occurs in the front shock absorber near the hand position, and show the obvious effect of the shock absorber to reduce the PSD values and improve the comfort level.