Statistical investigation on the coupling mode characteristics of a blade-disk-shaft unit

The coupling vibration of a blade-disk-shaft unit is generally studied on the assumption that all the blades are identical. However, the mistuning feature always occurs due to manufacturing tolerances and other reasons in engineering practice. Therefore, a shaft-disk-blades coupling model with the random mistuning feature is derived based on our previous work. Then the statistical analysis on vibration characteristics of a blade-disk-shaft unit is performed. The uncertainty effects of blade parameters on coupling characteristics between the subcomponents are exhibited. The Monte Carlo simulation and statistical theory are used to capture the probability distributions of coupling characteristics. The natural frequency distributions of coupling modes are obtained under different mistuning levels and evaluated through confidence intervals. Then the mode shapes, obtained by eigenvector, are plotted to derive the evolution law of coupling mode type in a random mistuning system. At last, the localization factor is defined, then its statistical results are obtained to evaluate the mode localization magnitude under different mistuning levels.