Application Of Modal Analysis And Parameter Identification In The Field Of Railway Vibration

With the development of track traffic, the deformation and destruction of track system is speeded up consequently. The major reason of track invalidation is the track vibration. Due to the higher demand of track capability, it is needed to search the dynamic characteristic of track system. In general the track structure consists of track, rail pad, sleeper and ballast and it is a very complex structure. It will be a valid method to constitute track structure dynamic modal and identify the modal parameters by modal analysis technology. Therefore based on modal analysis theory, the main ideas of this paper can be summarized as follows:1 The relations of physical parameter model, modal parameter model and non-parameter-model in vibration system have been researched. That s the problem of theoretic modeling of the three models. The real modal analysis and complex modal analysis are respectively applied to the multi-degree-of -freedom system according to the different damp. This chapter is the theory basis of the paper.2 Based on modal analysis theory of chapter two, several track models are simulated by ANSYS and the impact load, harmonic load and moving load are respectively put on the models. Then the time domain responses are transferred to the frequency domain by the FFT. Final, frequency, damp and mode shape of the several models are identified by half power method and MATLAB procedure. The identification results are compared with theory results, and the satisfied results have been got.3 The Eigensystem Realization Algorithm (ERA) is first applied to identify modal parameters of track structure in this paper. Then the basis theory process of this method has been deduced. The two-dimension track model and three-dimension track model are set up using ANSYS. After the several impulse responses are got by MIMO method. The frequency and damp ratio are estimated by constructing Hankel matrix and MATLAB procedure. Finally the identification results are compared with theory results, some useful conclusions have been got. From the results, we find out that this method is applicable to estimate the coupled-modes of railway system, therefore it is feasible to identify modal parameters of track by this method.In the end, the content of this paper has been summarized and some problems, which need further study, have been proposed.