Temperature- and frequency-dependent vibroacoustic response of aluminium extrusions damped with viscoelastic materials

Abstract

Viscoelastic materials are commonly used as damping materials for noise and vibration control in composite structures. However, their effective damping temperature range is usually extremely narrow, and a comprehensive understanding of their temperature- and frequency-dependent properties is lacking. Therefore, in this study, we analyse the temperature- and frequency-dependent vibroacoustic response of aluminium extrusions damped with viscoelastic materials. First, three kinds of modified butyl rubbers with the best damping performance at different temperatures were fabricated. Their glass transition temperatures were measured using differential scanning calorimetry, and their temperature- and frequency-dependent damping loss factors and elastic moduli were determined through dynamic mechanical analyses and using the time–temperature equivalence rule. Subsequently, to practically apply the viscoelastic materials to a high-speed train carbody, the heat transfer characteristics of aluminium extrusions were analysed using the finite element method, and the vibroacoustic behaviours of the composite structure were investigated considering the temperature- and frequency-dependent damping loss factors and elastic moduli of the viscoelastic materials. Finally, the key parameters of the viscoelastic materials that affect the radiated sound power of the composite structure were discussed, and multilayer damped aluminium extrusions using three different viscoelastic materials were analysed. The results demonstrate that in order to control the noise and vibration of composite structures over a wide range of temperatures, not only the temperature range and damping performance of viscoelastic materials should be broadened and improved, respectively, but also the damping loss factor and elastic modulus should be matched considering temperature and frequency variations.