Modal Randomness Induced by Boundary Conditions

The modal frequencies of a structure often exhibit random variation. This variation may be an important factor affecting structural response. This paper summarizes the results of a combined experimental and analytical study that considers modal frequency randomness arising from boundary condition random variation. It is shown that a simple measure of boundary condition characteristics can be used in connection with a finite element based analysis to estimate random variation in modal frequencies. A comparison between the experiment and the analysis confirms the accuracy of the analytical technique.