Removing mass loading effects of multi-transducers using Sherman-Morrison-Woodbury formula in modal test

Abstract

In the modal test of lightweight structures, the measured data is easily polluted by mass loading effects of transducers. A method is proposed to eliminate the influence of sensors for accurately estimating the frequency response functions (FRFs) of structures. Considering the situation that the multiple accelerometers lead to changes in the dynamic stiffness matrix, the corrected FRFs are derived from the original measured signals based on the Sherman-Morrison-Woodbury formula. The salient feature of the proposed strategy is that the adverse effects of sensors can be eliminated in only one step. Numerical simulations are conducted by employing a six-degrees of freedom spring-mass system, modal frequencies and mode shapes with high accuracy are obtained by measured signals. Experimental investigation is undertaken by using a laboratory solar panel. Results show that the effects of multi-transducers mass can be removed efficiently and the corrected FRFs are in good agreement with the targeted values. The excitation and measurement points are regarded as active coordinates, and the computational efficiency can be significantly improved when the presented method is applied on active coordinates.