Friction Damper Mistuning of a Bladed Disk and Optimization With Respect to Wear

Abstract

Friction damper mistuning is an area in which less research has been done compared to blade mistuning of bladed disks. Inspection of contact areas, on used platform dampers, indicates that their environment is strongly varying. This is mostly due to geometrical imperfections of the damper and contact surfaces on the blades, but also due to variation in mechanical properties of the blades. In this paper a parametric study is performed to investigate the effects of damper mistuning on blade vibrations. For this study a friction contact model which is valid for both microslip and macroslip is used. The result indicates that damper mistuning greatly affects the blade vibrations. It is also found that the optimal damper is the same for the tuned and the mistuned case. A comparison of blade and damper mistuning is also performed. The result indicates that blade and damper mistuning together constitute a more severe case than only blade or damper mistuning. Friction damper wear is investigated for a tuned bladed disk. The result demonstrates that the resonance amplitude can either increase or decrease depending on the properties of the damper. The wear process is also investigated for an initially blade mistuned case. The simulation result is compared to measurements from bench tests with a military jet engine. For a designer of a new damper it is important to know what should be expected when the damper is in use and gets worn.