Abstract: In order to eliminate the angle errors of doublet mode shapes which are obtained by finite element modal analysis and experimental modal analysis for cyclic symmetric structures and then realize accurately quantitative modal correlation analysis, the formation mechanism of angle error between mode shapes of doublet modes from different modal model is revealed and a new mode shape correlation correction method of cyclic symmetric structures is presented based on mode shape equations. The initial Cross modal assurance criterion (Cross MAC) value of each doublet modes between finite element mode shapes and experimental mode shapes is calculated. Angle errors and the corresponding point number which should be rotated are worked out. The corrected Cross MAC value and accurate analysis results of modal correlation for cyclic symmetric structures are achieved after matching the finite element mode shapes again. Taking brake disc as an example, the new method is applied to correct correlation between finite element modal model and experimental modal model. The results show that not only the correlation can be achieved accurately, but also the correction efficiency compared to existing cyclic group and elementary rotation transformation methods is increased.

Key words: angle error, correction, correlation, cyclic symmetric structures, modal analysis