Constrained-layer Dampers for Attenuation of Structural Vibration

Abstract

In a constrained-layer damping system, a thin layer of a viscoelastic material is applied over the vibrating substrate. and covered with a stiff constraininglayer of a metal or a fibre-reinforced plastic. Several viscoelastic materials based on elastomeric blends of copoly (acrylonitrilebutadiene) and polyvinyl chloride were developed. These materials were characterised for hardness, tensile properties, ozone resistance, and electrical and dynamic mechanical properties. Two polymer compositions were used to fabricate 1 mm sheets. The sheets were fixed on an aluminium substrate with a rigid epoxy glue. A fibre-reinforced plastic sheet of 300 p was fixed on the viscoelastic layer by a rigid epoxy glue. The experimental setup for the measurement of vibration response has been elaborated. The study was carried out with and without the constrained-layer damping system. The vibration attenuation achieved was to a minimum of 5-7 dB at 200-500 Hz and to a maximum of 9-16 dB at 3000 -4000 Hz for the selected constrainedlayer damping system.