Reduced-Order Modeling Friction for Line Contact in a Turbine Blade Damper System

Under-platform damper is used to attenuate resonant response and further prevent high cycle fatigue failure of turbine blades. The aim of this work is to improve the representation of contact interfaces in modeling an asymmetrical underplatform damper. A new reduced-order contact model with a lumped parameter form is proposed, which is based on a modification of the classical Iwan model. This model can explicitly consider the normal contact pressure on line contact. In modeling process, a method to relate the physical Hertzian normal contact pressure with the probability density function (PDF) of slider sliding force for continuous Iwan model is developed. Experimental results from a laboratory asymmetrical under-platform damper test rig are employed to validate the proposed model. For comparison, different normal contact pressure distributions are considered. The outof- phase motion of the damper is numerically investigated, and the results show that the proposed model can give an accurate prediction of the damper's nonlinear mechanics behavior.