Abstract
Modal parameters can reflect the dynamic characteristics of the structure and can be used to control vibration. To identify the operational modal parameters of linear slow-time-varying structures only from non-stationary vibration response signals, a method based on moving window locality preserving projections (MWLPP) algorithm is proposed. Based on the theory of “time freeze”, the method selects a fixed length window and takes the displacement response signal in each window as a stationary random sequence. The locality preserving projections algorithm is used to identify the transient modal frequency and modal shape of the structure at this window. The low-dimensional embedding of the displacement response data set calculated by locality preserving projections (LPP) corresponds to the modal coordinate response matrix, and the transformation matrix corresponds to the modal shape matrix. The simulation results of the mass slow-time-varying three degree of freedom (DOF) and the density slow-time-varying cantilever beam show that the new method can effectively identify the modal shape and modal natural frequency of the linear slow-time-varying only from the non-stationary vibration response signal, and the performance is better than the moving window principal component analysis (MWPCA).
Highlights
Vibration is an inherent property of structures and bad vibrations will cause damage to structures [1]
A method based on moving window locality preserving projections (MWLPP) is proposed to identify the operational modal parameters of linear slow-time-varying structures
(3) Comparing Figures 13 and 17, the natural frequency of the linear slow-time-varying structure changing with time, and MWLPP can well track the change of the natural frequency
Summary
Vibration is an inherent property of structures and bad vibrations will cause damage to structures [1]. The moving window method based on the theory of “short time-invariant” can be well applied to the identification of operational modal parameters of linear slow-time-varying structures. The moving window method has been applied to some algorithms to identify the operational modal parameters of linear slow-time-varying structures. A method based on moving window locality preserving projections (MWLPP) is proposed to identify the operational modal parameters of linear slow-time-varying structures. (2) The LPP algorithm and moving window method are combined to identify the operational modal parameters of linear slow-time-varying structures. When the value of each natural frequency is different, The normalized orthogonality and the modal of main each modal shape φ i satisfies other is independent
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