Identification and quantification of nonlinear stiffness and nonlinear damping in resonant circuits
This paper presents a study of nonlinear vibrating mechanical structures whose resonances have nonlinearities due to stiffness and/or damping. A method is presented to detect the presence of nonlinear distortions qualitatively and quantitatively. Basically, a device under test is configured as a second-order, single-inputsingle-output closed-loop feedback system where static nonlinearities are confined to the feedback path, and the dynamic linear part is modeled as the forward gain. The system is excited by a random phase multisine, which allows for the modeling of the linear part by its frequency response function, thus facilitating the characterization of the nonlinear part. The identification is formulated in a linear-in-parameters framework, using input and output regressors. A good agreement between the estimated data and the measurements indicates the presence of nonlinearities due to stiffness and damping with distinguishable levels.
nonlinear stiffness nonlinear damping measurements vibrating systems simulation best linear approximation