Abstract: Focusing on the defects of the classical modal parameter estimation approach, this paper investigates a novel technique for modal parameter identification of structures under operation conditions. Stochastic subspace realization is introduced to determine the system matrix only using output data. The performance of the method is critically evaluated for an airplane model. The results of experiment show that the above method has the same accuracy as the classical modal estimation method and possesses a broad application prospect in parameter identification of structures under operation conditions.

Key words: modal testing, subspace identification, ambient excitation