基于滑动时域窗和ERA的模态阻尼比辨识技术研究

Study on the Modal Damping Ratio Identification Based on Sliding Time Window Method and ERA

在使用环境激励进行模态辨识时,模态阻尼比辨识结果往往散布较大,其随辨识信号长度和不同信号段的影响较大;针对时不变系统,提出了采用带重复宽度的时域滑动窗口与统计方法结合的模态阻尼比辨识方法,提高模态阻尼比的辨识精度和稳定性;首先,详细介绍了ERA环境激励模态辨识方法的理论;其次,给出了时域滑动窗口与统计方法结合的模态阻尼比辨识方法以及工作流程;最后,通过算例验证了时域滑动窗口与统计方法结合的模态阻尼比辨识方法,并分析了其对信号噪声量级和信号信息量的鲁棒性。

The identification result of damping ratio is eurychoric while operational mode identification is investigated under ambient excitation,which is influence by the signal size and the different time. The operational mode identification method which is based on sliding time window method and ERA is investigated to improve the identification accuracy and stability. Firstly,the theory of the ERA method is introduced. Secondly,the strategy for decomposition and implementation is put forward,including the sliding time window method and the modes＇ filtration method. At last,an example is studied,where the cantilever beam is built and the white noise exciting is added. It is found that the mode can be realized by using the method,and the method has high robustness to the signal to noise ratio and signal size.