Based On Ar Model And Prony Method Of Structural Modal Parameters Identification

Modal parameter identification of vibration systems is one of the most important subjects in structural dynamics, which plays significant roles on structure modeling, model updating, sensitivity analysis, vibration control, damage detection and state monitoring, etc. In this paper, modal parameter identification by AR model and Prony method are studied and the main contents are detailed as following:(1) The identification of parameter model type, the determination of the model order and the estimation of model parameter are reviewed. Different types of models can be expressed as the AR model with sufficient high orders. The correctness of the identification method for model type, the criteria of order determination and the parameter estimation methods are investigated by digital simulation examples.(2) The AR model and the Prony method are applied to identify the modal parameters of the linear time-invariant vibration system. An approach to effectively remove the false modal is put forward. Simulation examples and experiments show the efficiency of the method. In addition, it is indicated that the Prony method has higher precision than that of the AR model to identify the parameters.(3) The time-variant Prony method to process non-stationary signals, the maximum likelihood criterion to determine the model order and the basis function dimension are studied. Simulation examples show that for different basis functions the precisions of parameter estimation and model parameter identification are different. The discrete cosine time (DCT) basis function is more precise than other functions.(4) Based on the DCT basis function, the frequency resolution and the anti-noise performance of the Prony method are researched. The experimental device comprising a cantilever beam and an adjustable additive mass is designed. The experiment on a cantilever beam with an adjustable mass are conducted. The modal parameters identified by the time-variant Prony method are compared with the modal parameters on the designated status and obtained by finite element analysis. It is indicated that the Prony method based on the DCT basis function is feasible in practice.