关键词: 运行模态, 弱响应模态, 传递率, 相关函数, 小波变换

Abstract:

In operational modal analysis, it was difficult to identify all of system modes, when close modes existed, weak response signal submerged in big noise, and the response data was short. Consequently, a new method which combining transmissibility function and correlation function to identify system modal characteristics (combine method) was proposed herein. Specifically, transmissibility function which approximated to FRF was calculated to get frequency characteristic function of the system weak response, and then wavelet transform was exploited to achieve weak modal identification. The numerical simulation experiment was implemented, which utilizing GARTEUR plane model with random excitation to simulate outputs data in operational condition. At last, the results show that, compared with the poly-reference least squares complex frequency domain algorithm, this combine method can identify modal frequency with high precision. At the same time, the accuracy of damping ratio identification is improved greatly. Especially, transmissibility is good at weak modal identification with close modes.

Key words: operational modal, weak mode, transmissibility, correlation function, wavelet transform