Structural vibration damping by the use of poro-elastic layers: a summary

Abstract

A properly designed limp porous materials such as fibrous layers can provide damping equivalent to conventional viscoelastic dampers while providing advantages such as light weight and effective sound absorption. This then allows porous layers to be used as multi-functional noise and vibration control solutions in automotive and aerospace applications. Further, the addition of bulk elasticity to the solid phase of the porous medium is beneficial since it improves damping performance compared to equivalent limp treatments. In the work summarized here, porous media, such as fibers and foams, were designed to serve as treatments for various vibrating structures to examine their damping effectiveness. Both analytical modeling and numerical simulation based on finite element methods were involved depending on the complexity of the structure. Specifically, a Fourier transform-based computational method was introduced as the key step to allow accurate prediction of a panel's spatial response based on its wavenumber-frequency spectrum. Parametric studies have been conducted to identify the optimal bulk properties that would allow a porous layer to provide the largest possible damping within a target frequency region. Finally, design concepts for achieving the maximum damping potential of porous layers are summarized.