Modal Analysis Using Operating Modal Identification Method

Sometimes it is very difficult for some large scale operating structures to measure the input forces. Modal parameters must be estimated on response only. A poly-reference time domain operating modal identification complex exponential method is presented since cross-correlation functions have the same form as impulse response functions. Then a poly-reference frequency domain operating modal identification method is proposed in this paper. An experiment on an aircraft model is performed to verify the proposed schemes. The results show that both outlined schemes can extract the parameters from output-only and the modal parameters extracted by proposed frequency-domain method are more accurate than those by presented time domain complex exponential method.