Forced response analysis in time and frequency domains of a tuned bladed disk with friction dampers

A micro-slip model of a friction damper is presented in this paper. There are two formulations derived from the original force and displacement functions of the damper: a numerical blade-to-blade model and a linearized blade-to-ground model. The numerical friction damper was used in a time domain simulation of the forced response of a beam-damper system under travelling wave excitation. Frequency domain simulations with one blade and the blade-to-ground damper were also carried out. Simulation results agree well, except around the optimal damper weight, which is the weight that minimizes the response amplitude of the blade and damper system. Results from frequency domain simulations give a lighter optimal damper weight than the time domain simulations. This leads to the conclusion that if frequency domain simulations are used to find the optimum damper weight, then a slightly heavier damper weight should be chosen than suggested by frequency domain results. Comparison between a microslip and a macroslip model for the friction interface shows that the macroslip model gets close to predicting the optimal weight, but the response level is much higher than when the microslip model was used. (C) 1998 Academic Press.