Identification of Nonlinear Damping Using Nonlinear Subspace Method

In this paper, the identification problem is discussed for damping nonlinearity. In practical applications, nonlinear damping is widespread, which is inevitable in the vibration response. Within the wide range of nonlinear damping mechanisms, friction is surely one of the most common, and with a high impact on the dynamical behavior of structures. Two common kinds of friction are investigated: quadratic friction and Coulomb friction. Nonlinear damping parameters are identified by nonlinear subspace identification, where the damping nonlinearity of the system is considered as a feedback force applied to the underlying linear system and is identified utilizing the time domain data. Two simulation examples are conducted to verify the effectiveness of the method. Results confirm the effectiveness of the methodology in identifying damping nonlinearities.