Identification of Nonlinear Structures by the Conditioned Reverse Path Method

The modeling method and identified method adapted to multi-degree-of-freedom structures with structural nonlinearities are established. The free-interface component mode synthesis method is used to establish the nonlinear governing equations by extending the connected relationships. Based on the modeling method, the conditioned reverse path method is used to identify frequency response functions of the nominal linear system without the influence of nonlinearities, and the parameters of nonlinearities are identified in the frequency domain. Nonlinear analysis and identification of a typical folding wing configuration with three free-play hinges are investigated. The nonlinear governing equation is established based on present methods, and the computational results are checked by finite-element programming. Based on coherence function, the effects of a nonlinear function are evaluated. The frequency response funtion of the nominal linear system and parameters of the nonlinear function are identified by the conditioned reverse path method within the noise signal. A ground vibration test of an all-movable fin is performed. The results show that the extending component mode synthesis method in the present work could be used to establish governing equations with structural nonlinearities. Based on the modeling method, the conditioned reverse path method can be used to identify the structural nonlinearities accurately.