- 會議論文
運用雷射位移計量測及分析樑結構產品的動態特性
Use the Laser Displacement Sensor to Measure and Analyze The Dynamic Properties of Beam Structure Products
摘要
本文之主要目的乃是探討樑結構產品的動態特性，以市面上現有的樑結構產品進行實驗模態分析。將理論分析、有限元素數值分析法與實驗量測分析法三者所得的結果作比較驗證，探討所模擬的樑結構產品模型邊界的正確性。整體的實驗架設是以小型激振器對懸臂樑結構輸入由函數器所產生的外力訊號，同時透過雷射位移計與加速規的量測輸出資料至頻譜儀器進行振動模態分析。振動模態分析一般有兩種方法。第一種是數值分析計算法，其中最常用的為有限元素法。第二種是頻譜儀器量測法；數值分析計算法現今大都利用電腦軟體模擬，如ANSYS、COSMOS 和NASTRAN等商業化應用軟體，但是在對於較複雜的結構或是接面較多（如螺絲、轉動軸、滑塊等）的結構時，計算法就會失去其精準度，這就是電腦模擬還是無法完全取代頻譜儀器量測法的原因。
並列摘要
The main objective of this paper is to present a method to find the modal properties of beam structure products. We use the beam structure product in market to perform the experimental modal analysis ( EMA ) and verify the accuracy of the boundary conditions of the beam structure products. The modal testing of the beam structure product is performed by giving a harmonic force signal to shaker and fixing the optoelectronic laser displacement measurement system. A series of frequency response functions (FRFs) is obtained as well as the corresponding coherence functions. By the finite element numerical analysis, the structural modal parameters can be determined. Results show that the experimental and theoretical results, including FRFs, natural frequencies, modal damping and mode shape, agree well. The constructed beam structure products are validated and can be used as the demonstration tools of vibration measurement and EMA as well as for the further study of the structural vibration control. There are two methods are mostly used in vibration analysis. The first one is the numerical analysis method, and finite element method is the common used method. The second one is the frequency spectrum instrument measurement method. The numerical analysis method is the mostly used computer simulation method. Now, the commercial softwares constructed by using this method are ANSYS, COSMOS/M and NASTRAN etc. Some complicated structures or face-contact structures by using numerical analysis method will lose its accuracy. That is the reason why the computer simulation can’t completely replace the frequency spectrum instrument measurement method.