HARMONIC-BALANCE VIBRATION ANALYSIS OF TURBINE-BLADES WITH FRICTION DAMPERS

Although considerable effort has been devoted to the formulation of pr edictive models of friction damper behavior in turbomachinery applicat ions, especially for turbine blades, the problem is far from being sol ved due to the complex nonlinear behavior of the contact surfaces. Thi s paper primarily focuses on analytical and numerical aspects of the p roblem and addresses the problem in the frequency domain while explori ng the viability of equivalent time-domain alternatives. The distinct features of this work are: (i) the modelling of nonlinear friction dam per behavior as an equivalent amplitude-dependent complex stiffness vi a a first-order harmonic balance method (HBM), (ii) the use of sine sw eep excitation in time-marching analysis, (iii) the application of the methodology to numerical test cases, including an idealised 3D turbin e blade model with several friction dampers, (iv) the verification of the numerical findings using experimental data, and (v) a detailed ass essment of the suitability of HBM for the analysis of structures with friction dampers.