59863 - Identification of Slip Load, Friction Force and External Force Using Unscented Kalman Filter for a Frictionally Damped Turbine Blade 

    An Unscented Kalman Filter (UKF) based technique has been developed for parameter estimation of turbine blades with friction dampers. The technique  is based on integration of Newmark method, an iterative numerical integration method for structural dynamics, with UKF.  The technique has been implemented on a  single mode model of a turbine blade with a friction damper. Two approaches are developed. First, both steady state vibration and known forcing data are used to estimate parameters such as friction force and  slip load. These parameters are treated as additional  states of the system and augmented state space model is used with UKF to estimate parameters. In the second approach, transient vibration response of the system is used to estimate  slip load, friction force  and  unknown sinusoidal forcing function as well. The frequency of  sinusoidal external excitation is assumed to be known. The unknown magnitude and phase of the external excitation are represented as a solution of a second order differential equation, which leads to two additional states in the model. Numerical results are presented for both the cases of known and unknown forcing functions at different levels of modeling and measurement errors. A discussion of these results is presented and  the validity of the new approach is corroborated.