RESPONSE SPECTRAL DENSITIES AND IDENTIFICATION OF A RANDOMLY EXCITED NONLINEAR SQUEEZE FILM OSCILLATOR

The concept of linear systems with random coefficients is used to obta in an analytical approximation of the power spectral density (PSD) fun ction of the response of an oscillator with non-linear inertia, dampin g and stiffness terms. To identify the parameters involved in the non- linear terms, a procedure is described, which consists of fitting the response PSD to the experimental one after suitably predetermining the parametric values. The direct and inverse procedures are presented in the context of an oscillator with squeeze him force dynamic. Identifi cation was performed from experimental data with various film thicknes ses and excitation levels. The experimental PSD function of the squeez e film force is not required with this procedure. The parameters ident ified yield a squeeze film force PSD which was in good agreement with the experimental one. (C) 1998 Academic Press.