Modal parameter identification of mistuned bladed disks using tip timing data

Two methods for the identification of the vibration characteristics of rotating engine blades from time response measurements are presented. The time responses are obtained from a mathematical blade tip timing simulation which is developed using a multi-degree-of-freedom model including structural properties of the bladed disk assembly, blade mistuning effects and aeroelastic terms. The modal parameters are identified from two subspace algorithms. The first subspace algorithm uses the properties of the shifted observability matrix. The second subspace algorithm optimizes the mutual information between the future data vector of observations and the innovation state vector. The results from the methods are compared in order to determine which of the methods is more suitable in modal parameter identification of rotating engine blades.