Instantaneous modal parameter identification based on parameter optimized variational mode decomposition
In view of the problem of determining the modal number and quadratic penalty factor of variational mode decomposition(VMD),a parameter optimization algorithm based on orthogonality index,energy ratio and variational energy entropy(VEE)was proposed.For the decomposed single component signal,the instantaneous frequency identification method based on polynomial chirplet transform(PCT)and the instantaneous damping ratio identification method based on energy method were developed.The simulation research of 3-DOF(degree of freedom)time-varying structure and the experimental research of time-varying steel beam were carried out.The results showed that the optimized VMD method can accurately separate the time-varying components of the multi-DOF system with strong anti-noise performance.The instantaneous frequency identification method based on PCT had strong time-varying frequency tracking performance,strong anti-noise ability,and high accuracy of time-varying frequency identification,and the average error was less than 1％.The energy method can accurately identify the instantaneous damping ratio of the structure with obvious anti-noise advantage,and the identification error was maintained at about 10％.
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