Host: The Japan Society of Mechanical Engineers
Name : Dynamics and Design Conference 2023
Date : August 28, 2023 - August 31, 2023
Although bladed disks are nominally designed to be cyclically symmetric (tuned system), the vibration characteristics of all blades on a disk are slightly different due to the manufacturing tolerance, deviations in the material properties, and wear during operation. These small variations break the cyclic symmetry and split the eigenvalue pairs. Bladed disks with small variations are referred to as a mistuned system. Many researchers suggest that while mistuning has an undesirable effect on the forced response, it has a beneficial (stabilizing) effect on the blade flutter (the self-excited vibration). If the total damping of a bladed disk becomes negative, the bladed disk becomes unstable, and consequently the blade flutter occurs. However, it is well known empirically that, in an actual bladed disk with the friction damping, the amplitude of the blade flutter is saturated due to the friction damping, and the limit cycle oscillation (LCO), i.e., the steady vibration with a constant amplitude occurs, even if the total damping of a bladed disk is negative. In this paper, the effect of the mistuning and the friction damping on the flutter amplitude is studied systematically using the method of multiple scales and the equivalent spring-mass model of a blade disk with the friction damping between the root and disk. From the analysis results, the effect of the mistuning and friction damping on LCO is elucidated.
