Åsa Bolmsvik

Damping elastomers for wooden constructions : Dynamic properties

Abstract Elastomers are commonly used to decrease the sound transmission between apartments in timber framed houses. In previous studies, different types of connections have been evaluated. However, the frequency dependent dynamic properties in different directions of a connection including elastomers are not fully investigated yet. Previous studies have actually shown that elastomers cause the vibrations to increase in the direction perpendicular to the applied load within the low frequency span. The properties of the elastomers are needed in order to model the dynamic behaviour and thereby be able to predict sound and vibration transmissions in wooden houses in the future. With known properties, the elastomer connections can be modelled using springs and dashpots. In this study, dynamic experiments have been made on elastomer strips half embedded. The test setup has been subjected to various loads using an electromagnetic shaker. The responses have been measured and evaluated using modal analysis. With different loads, non-linear characteristics of the elastomers’ behaviour have been obtained. The elastomers have also been tested quasi-statically, to obtain a load-deflection curve. Finally, the estimated properties of the elastomers have been included in an FE model using springs and the analytical results are compared with the experimental results.

Structural Vibrations of Wooden House Walls

The flanking transmission between apartments due to a structure borne source is studied. The apartments studied were two-storey houses with a wooden framework. Acoustic measurements are often made in new built apartments to make sure that they fulfil the building regulations. Traditional measurements give no information about the contribution of the surrounding walls to the sound transmission. This paper describes a method of measuring flanking transmission. The acceleration levels on the receiving parts in the apartment below the source are studied. Thereby the contribution to the sound pressure in the room from each flanking part can be distinguished.