Study of Operating Modal Parameter Identification

It is difficult for the traditional methods to identify modal parametes of structures with overlap modal frequencies and high modal damping.With incentive-based environmental random subspace method and Polymax algorithm,this paper studied the changes of modal parameters(modal frequencies,modal damping ratios and mode shapes) in different conditions.Random subspace method is a time-domain modal identification method,and in identification of adjacent modes,it is better than some traditional modal identification methods.On the other hand,Polymax,which is also called polyreference least-squares complex frequency domain method,has a clear advantage in damping ratio identification.The comparative experiment study of an cantilever proved their effectiveness and reliability under different excitation conditions.