A novel test rig for friction parameters measurement on underplatform dampers

Abstract

The focus of this paper is on the direct experimental investigation of underplatform dampers, friction damping devices used on turbine bladed disks to limit resonant vibrations. Given the nonlinear and highly complex nature of dry friction, model validation of bladed disks with underplatform dampers still relies heavily on experimental verification, which is typically performed using the Frequency Response Function.This paper is the authors’ most recent effort to increase the understanding of friction and damper mechanics by gathering experimental evidence directly at the blade platform/damper interface.A new test rig for frequencies and contact pressures in line with real working conditions has been developed. The geometry of the test rig and its technical features are described in detail in the paper. The dedicated experimental evidence thus obtained is used to estimate (not tune) contact parameters. The influence of frequency, centrifugal load and of the flat-on-flat contact interface morphology is highlighted. Results are compared with those gathered using similar dampers on a different test rig. Contact parameters are then be fed to a state-of-the-art numerical code for the prediction of the dynamic response of friction damped systems. The experimental-numerical comparison is used as validation and as a basis to investigate the simulation sensitivity to contact parameters variability.