Phase resonance method for linearized identification of nonlinear mechanical structures

Kurzfassung

Ground Vibration Tests provide data to validate the prediction of structural dynamics of the aircraft before first flight. For this purpose, a modal substitute model is identified from experimental data. However, nonlinear dynamic behavior is often observed during those test campaigns, resulting in frequency and damping variations for specific modes. %uncertain results. This work deals with the modal identification of aircraft with structural nonlinearities. Phase resonance method is embedded into the theory of describing functions for an improved linearized identification. Also, modal phase control is employed for automatic tuning of the excitation frequency in phase resonance testing in order to speed up the identification process. This methodology is then applied to aircraft structures and the results are discussed in the context of the assumptions made within this work. Improved results are achieved with a laboratory structure, while limits of this method are found with a real airplane structure.