Numerical prediction of the vibroacoustic of sandwich panels with add-on damping

This paper discusses the numerical modeling of the vibroacoustic response of sandwich panels with add-on damping, under two types of excitations: Point load, and acoustic excitation, diffuse acoustic field. The studied damping is of the form of a viscolaetsic layer located within the panel. A modal synthesis approach is used for the calculation of the structural response and the Rayleigh's integral is used for the acoustic response (the panel is assumed flat and baffled). Since the panel has a viscoelastic core, a methodology is presented to handle efficiently the modeling of the frequency depended properties of the viscoelastic layer. A direct frequency response is used to validate the proposed approach. Next, a parameters study on the effect of the viscoelastic layer location is presented, In particular, three locations are compared: within the Honeycomb core, within the skins and added to the skin with a constraining layer. The effects of the excitation type on the vibration and acoustic response are also discussed. Key words: Sandwich NIDA, Modal FEM method, viscoelastic damping, acoustic response