基于正交多项式和稳定图的密集模态参数辨识

Modal Parameter Identification of Closely-Coupled Modes Based on Orthogonal Polynomial and Stabilization Diagram

由于正交多项式算法在频响函数模态参数拟合时,模态数目和多项式分子阶次较难确定,无法对拟合过程进行干涉。在原有算法的基础上,通过结合稳定图和模态指示函数,确定了频响函数的模态数目和极点(阻尼及固有频率);在已知极点的基础上,由线性最小二乘方法对留数进行估计。此外,该方法被扩展到频响函数的整体拟合。通过将该方法应用于模态耦合严重的频响函数模态参数估计,并与原有正交多项式算法及商业化软件M E’scopeVES进行对比,表明该算法在避免虚假模态或发生模态遗漏现象的同时,拟合结果准确、稳定,抗干扰能力强。

The orthogonal polynomial method is widely used in the identification of modal parameters performed on the frequency response function(FRF) curves.The disadvantage of this method is difficult to determine the number of modes and the order of the polynomial,while it is difficult to intervene with the identification process by the operator,which can result in the omission of some modes or occurrence of false modes.In this work,based on existing algorithm,the number of modes and poles of the FRF is first determined by use of the stabilization diagram and mode indicator function(MIF) in a combination way,and then the residue is estimated by using linear least square method.Furthermore,this method is extended to the global FRF curve-fitting.A comparison of the modal parameters estimated from a measured FRF by using existing orthogonal polynomial algorithm or the commercial software ME′scope VES to those estimated by the method suggested in this work shows that the phenonmena of false modes and the omission of some modes no longer occur to the results given by the method besides that it can get accurate and stable results,and has great anti-disturbance ability.