The Development Of In-plane Vibration Measurement System With Laser Doppler Vibrometer

This thesis is a part of the National Natural Science Foundation (No. 50235010) : The development of in-plane vibration measurement system with Laser Doppler vibrometer.Currently, the research of such USM based on in-plane vibration mode needs to test the in-plane vibration mode, and the other types of USMs also need to check whether there existing such in-plane vibration mode, which is useless and leads to inefficiencies.The 3-D laser vibration measurement system of the Polytec company could be used to test the in-plane vibration mode of the stator of USM, but it is very expensive.Based on the above reason, the main works of the thesis are summarized as follows:(1) Analysing the characteristics of in-plane vibration mode and using the laser sensor head LSV065-306F (Polytec Company)to develop a measurement system which could be used for in-plane vibration modal testing.(2) According to the good characteristics ( rapid response,self-locking and etc.) of USM, we use two traveling wave type rotary ultrasonic motors(TRUM) as the driver of the X-Yworktable, which can reach 2μm in precision.(3 ) Using DDS technique to generate incentive signal for modal testing; using radix-2 FFT algorithm to handle sweep signal, then we can get the Amplitude- Frequency map. Through the Amplitude- Frequency map, we can find the modal frequency; using the Least-squares fitting method to get the amplitude and phase of every point, then drawing the modal shape.(4) Using the measurement system to measure some stators and achieving good results.