Study on the Vibration Characteristics of Bladed Disks With Damping Mistuning

Abstract Bladed disks with slight blade variations are referred to as a mistuned system. Many researchers have suggested that while mistuning induces an undesirable effect on the forced response, it provides a beneficial (stabilizing) effect on the blade flutter (self-excited vibration). However, almost all studies have focused on the deviation in the blade frequency, and few studies have investigated damping mistuning. In a blisk (integrally manufactured bladed disk), damping mistuning appears to be negligible because material damping is dominant and its deviation is small. However, in a bladed disk where the blade root is inserted into the disk groove, damping mistuning caused by partial contact between the root and groove during rotation cannot be neglected in predicting the resonant response of a bladed disk. Some works suggest that the structural damping of a root-type bladed disk measured using the half-power method during rotation tests largely fluctuates in each individual blade. Damping mistuning may also affect the stability of the blade flutter. Therefore, in predicting the stability of a blade flutter, the effect of damping and frequency mistuning should be considered. From these backgrounds, in the current study, by incorporating the damping mistuning into a reduced-order model, namely, fundamental mistuning model, frequency response and stability analyses of bladed disks are systematically performed. From the calculated results, the effect of damping mistuning on the forced and self-excited vibrations of bladed disks is clarified. In addition, although the authors proposed a simultaneous optimization method for mistuned bladed disks for forced vibration and amount of unbalance in a previous work, damping mistuning was not considered. In the present study, the robustness of an optimal mistuned system for damping mistuning is also evaluated.