Vibration and Sound Radiation of Visco-Elastically Damped Plates : Sound Radiation from Finite Plates Excited by a Random Point Force

Abstract

The acoustic radiation from baffled finite plates with free visco-lastic damping layers excited by a random point force have been studied in order to evaluate damping treatment performances under the condition of neglecting fluid loading due to the back reaction of the radiated acoustic pressure. The plates are rectangular and clamped at the boundaries. The vibration responses of plates with damping layers are obtained by the finite element method. Modal damping ratios are estimated from undamped normal mode results by means of the modal strain energy method.The expressions for the surface acoustic intensity and the radiated sound power are derived in the transform formulation and evaluated numerically from the discrete Fourier transform of the vibration velocity responses of the plates in the spatial co-ordinates. An experimental study is carried out to measure the surface intensity distributions and to compare them with the analytical results.