| Summary: | 碩士 === 中原大學 === 土木工程研究所 === 94 === The transportation system of the track characteristic is convenient, swift and on time. Today it has already become a part of indispensable in people’s life. The high speed train going emphasizes the importance of the structure system maintenance.
The purposes of measuring the structure system of the rail are the train security guarantee, comfortableness in the course of going, disaster prevention and calamities avoidance. Accordingly, the new method which is vibration mode analysis - HHT (Hilbert Huang Transform) is proposed. This method uses the Hi-Tech vibration detecting instrument and does nondestructive inspection test.
The main purpose of this research is to expect the preliminary discussion on the frequency of rail every direction before analyzing vibration by the test of the laboratory simulation and in-situ dynamic train test with the HHT vibration mode analysis and traditional Fast Fourier Transform analysis applied in this study. With the range of frequency, next step is to focus on in-situ test plan which is trying to find out the position and distance of accelerometer installation to reach effective measures by the sub ballast arrangement irregularity or hollow of sub ballast which causes the rail non-smoothly. If the outcome of this study can confirm the damage position with vibration signal and prove the feasibility and suitability of the track vibration analysis will be discussed.
According to the result of study proves that the rail in the vertical direction and horizontal direction have the same frequency range definition with the references, and the main frequency range is influence on inside stress of axial direction probably 1200~1600 Hz, and by in-situ dynamic train test learn accelerometer at rail effective on quantity examine laying ranging interval between 8 m, so it is not good for the economic benefits, setting up the accelerometer on the top of the locomotive can measures effectively.
As the result of study it proves the relatively analysis of the traditional Fast Fourier Transform, Average natural frequency that the frequency received has nothing to do with time, It can not find the damage position with vibration signal effectively,However, Instantaneous frequency and energy scale could be obtained as the variation of time by HHT, by this way you can calculate the damaging position in the rail structure. Therefore HHT vibration mode analysis method can get the better analysis.
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