Experimental Mistuning Identification in Bladed Disks Using a Component-Mode-Based Reduced-Order Model

This paper presents two methods for identifying blade mistuning using measurements of the vibration response of an entire bladed disk. These methods are especially suitable to blisks, in which individual blades cannot be easily isolated. The first method makes use of measurements of the free response normal modes of the system, whereas the second is an extension of the first to make use of steady-state forced response measurements. For both methods,the variations in blade modal stiffness (the natural frequencies of the blades themselves) are calculated by converting a small set of measured blade vibration amplitudes into coordinates in a highly reduced-order model in which the blade modal stiffnesses appear explicitly. The effectiveness of both methods is demonstrated experimentally.