EMD method on identifying natural frequency and damping ratio of vibration mode

MO Pingjie, YANG Shixi, CAO Chongfeng
(Department of Mechanical Engineering, Zhejiang University, Hangzhou 310027, China)

Abstract: In order to indentify the modal parameters of the mechanical systems, a modal parameter identification method based on the empirical mode decomposition (EMD) was investigated. The EMD method was employed to decompose the vibration signals of a mechanical system under impulsive excitation. Different modal components with lower orders were picked up, and then the Hilbert transform was applied to identify their natural frequencies and damping ratios from the intrinsic mode functions (IMF). The modal analysis by ANSYS was firstly performed on a simply supported beam. Then, an arbitrarily chosen transient dynamical response of the system was decomposed and the modal parameter was identified by the EMD method. Comparisons between the results from the theoretical predictions, the ANSYS and the EMD show that, the EMD method can be used to perform the modal analysis of such system effectively.
Key words: empirical mode decomposition(EMD); modal analysis; natural frequency; damping ratio