The Studies on Structural Vibration Monitoring System and Mode Shapes Testing Method

Abstract: On the basis of the review of the present situation and existing problems of structure monitoring system, the paper makes a preliminary study of structural vibration monitoring system and puts forward a new mode shapes testing method. Data acquisition, analysis and processing are integrated in structural vibration measurement and analysis system including frequency spectrum, correlation and power spectrum analysis of time signals of testing positions. The total structural behavior is constructed and structural mode shapes, whose natural mode is known, are decomposed and monitored. Structural vibration measurement and analysis system lays the foundation of structural vibration real-time monitoring system that can monitor the total structural behavior, mode shapes, time and frequency signals. The paper introduces the basic principle and the implementation of the two above systems in detail. A method to construct mode shapes based on time domain signals of key positions is brought forward. Firstly, frequencies of each mode shape are gained through frequency spectrum analysis of time domain signals of key points. Secondly, time domain signals, which correspond to structural mode shapes, are gained through band-pass filter technology. Lastly, the corresponding mode shapes of each natural frequency are constructed by using time domain signals, which are processed by band-pass filter technology. In order to testify the validity of the method, the paper takes a cantilever for example and obtains a satisfying result…
Key words: structure monitoring; spectrum analysis; band-pass fiIter; mode shapes testing

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