Parametric Study and Uncertainty Quantification of the Nonlinear Modal Properties of Frictional Dampers
Résumé
A numerical methodology is described to study the influence of the contact location and contact condition of friction damper in aircraft engines. A simplified beam model is used to represent the blade for the preliminary design stage. The frictional damper is numerically analysed based on two parameters, contact angle and vertical position of the platform. The nonlinear modal analysis is used to investigate the nonlinear dynamic behaviour and damping performances of the system. Harmonic balanced method with continuation technique is used to compute the nonlin-ear modes for a large range of energy levels. Using such a modelling strategy, modal damping ratio, resonant amplitude and resonant frequency are directly and efficiently computed for a range of design parameters. Monte Carlo simulations together with Latin hypercube sampling is then used to assess the robustness of the frictional damper, whose contact parameters involve much uncertainties due to manufacturing tolerance and also wear effects. The influences of those two parameter are obtained and the best performances of the frictional damper can be achieved when the contact angle is around 25 •-30 •. The vertical position of the platform is highly mode-dependent and other design considerations need to be accounted. The results have been proved that the uncertainties involved contact surfaces do not have significant effects on the performance of frictional damper.
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