Unsupervised identification of arbitrarily-damped structures using time-scale independent component analysis: Part I

In this study, a new method is proposed to identify the dynamic parameters of structures with higher accuracy compared to current methods. First, the wavelet-transformed representation of system responses is extracted from measured responses, and then the independent component analysis is used to achieve the modal characteristics. The simulation results of a multi-degree-of-freedom system illustrate that this method is capable of accurately identifying the modal information of lightly- and highly-damped structures. It is represented that continuous wavelet transform, due to its adaptive time-frequency resolution, is more efficient to be incorporated into independent component analysis compared to Short time Fourier transform (STFT). The latter is unable to accurately determine the modal response, especially at higher frequencies, while the proposed method can identify the system with marked accuracy. The efficiency of proposed method is also investigated under additive noise. Results shown that for highly- and lightly- damped system, the proposed method is able to capture the modal parameters especially in higher frequencies of vibration, along with the modal assurance criterion values with satisfactory accuracy, which indicates the robustness of the procedure compared to other available methodologies.