The Effect of Air on the Nonlinear Response of a Plate

Abstract

*† ‡ This paper presents the results of an experimental study of the high-amplitude, random response of a clamped plate in air pressure conditions ranging from atmospheric to nearvacuum. Experimental results are compared to a reduced-order nonlinear model based on the implicit condensation and expansion (ICE) method. Linear modal damping ratios for the plate are estimated as a function of air pressure in the vacuum chamber and used in the model. In previous work a low-order nonlinear model incorporating a nonlinear damping term was shown to improve the predicted response of the plate in air. In the near-vacuum environment, the model is accurate without nonlinear damping. It is concluded that coupling with the air is the cause of the apparent nonlinear damping and acoustic radiation damping is the most likely mechanism. However, no conclusive evidence of nonlinear acoustic radiation is found.