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Dynamic Analysis and Application Of Helical Spring Isolator
|Authors: ||Chung-Kai Fang|
|Contributors: ||NTOU:Department of Systems Engineering and Naval Architecture|
|Issue Date: ||2011-06-30T07:32:57Z
|Abstract: ||摘要 螺旋彈簧具有六自由度之彈性，故用作隔振器時，可吸收六自由度之振動能量。本文主要在探討螺旋彈簧在六自由度之彈簧常數，及其隔振特性的分析。同時並將彈簧隔振器應用於高速遊艇軸系艉I架之隔振，並分析其隔振效果及與實驗值比較，驗證分析模式之正確性。 彈簧隔振器的隔振原理與其自然頻率有關，彈簧之自然頻率為 ，其k即分別代表六自由度之彈簧常數。當物體激振頻率與彈簧的自然頻率比大於4時，可以達到90％以上的隔振效果。M為有效質量，利用樑的線性疊加原理計求出有效質量。使用Ansys電腦軟體將軸系隔振之數值模擬，其分析結果與陸上實驗結果誤差約為10％~15％。 由陸地上I架減振實驗結果，軸系受衝擊負荷時，底板振動加速度在最高五大峰值之減振效果在4.4∼59.8dB之範圍。軸系受水平及垂向激振力時，底板振動加速度及角加速度在前五大峰值有40％~99％良好的減振效果。|
Abstract The helical spring possesses 6 degrees of freedom, thus when it is used as an isolator, it can absorb the vibration energy in 6 degrees of freedom. This article aims at discussing the spring constants of the helical spring at 6 degrees of freedom, as well as analyzing its vibration isolation properties. Meanwhile, the spring isolator will be applied to the I-frame of the shaft of a high-speed yacht to isolate the vibration. The isolation effectiveness is analyzed and compared with the experimental values to verify the correctness of the analysis model. The vibration isolation principle of the spring isolator is related to its natural frequency. The natural frequency of the spring is , where k represents the spring constants of the 6 degrees of freedom respectively. When the ratio of vibration frequency of a body over natural frequency is larger than 4, a vibration isolation of over 90% can be achieved. While M is an effective mass supported by the spring isolator, which can be derived by utilizing the superposition principle of beam theory for case of shaft system. By using the computer software Ansys, the numerical simulation of the shaft’s vibration isolation is carried out, and the maximum error between the results of the analysis and the results of the land based experiment is approximately 10%~15%, which was mainly resulting from the assumed value of damping ratio and basically it was proved the feasibility of the computer analysis. The result of I-frame’s vibration reduction experiment conducted on land shows that when the shaft is subjected to impulsive load, the vibration reduction of the vibration acceleration of the base-plate at the first 5 major peak vibration values is between 4.4~59.8dB. When the shaft is under horizontal or vertical excitation force, the first 5 major vibration values of the base-plate have attained a good vibration reduction in the range of 40%~99% in linear acceleration and angular acceleration.
|Appears in Collections:||[系統工程暨造船學系] 博碩士論文|
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