Optimisation of passive and active constrained layer dampers for panel vibrations over broad frequency and temperature ranges

Abstract

*† ‡ § This paper ex tends current understanding of optimum constrained layer damping (CLD) coverage for beams to more complicated strain regimes and applies it to panel vibrations. The ratio between the shear stiffness of the viscoelastic layer and the extensional stiffness o f the constraining layer is shown to be an important parameter in finding optimum performance. The Differential Evolution algorithm is used to locate and size CLD patches on a plate. The effectiveness (added damping over added weight) is plotted against sh ear parameter to demonstrate compliance with optimum shear stiffness hypothesis. A numerical study is used to show that active CLD requires higher shear stiffness in the viscoelastic layer. High damping is also noticeable in passive systems around the del amination frequency where the shear stiffness ratio is very low. For active CLD systems however, it is shown that the through -thickness region is best avoided. Above the delamination zone, the active layer has no effect while at the delamination zone itsel f, the control effort sometimes be to increase vibration effect.