Vibration Damping

In many cases, it is a very efficient and economic solution to the noise problem of applying an absorbing layer to a noise radiating surface. The viscoelastic properties of damping layer used for absorbing mechanical vibrational energy, which is hereby converted to heat. Swedac has several suitable materials for structure borne noise of several different types of structures.

As a measure of this energy absorbing capacity indicated loss factor which can be described as the surface of a hysteresis * formed when the damping layer stretched and compressed by the shear force during bending vibration. (* The relationship between two quantities of which one has a time lag following the other’s periodic change).

Typical construction materials such as steel, aluminum and fiberglass reinforced plastic has a loss factor of between 0.005 and 0.01. By laminating with a viscoelastic damping layer, the loss factor increased to 0.1-0.3 giving a reduced radiation of noise at resonance with 8-18 dB. In order to obtain acoustic properties the damping layer shall be provided with a rigid layer and form a “sandwich” construction. The layer is usually of the same material as the basic structure. The layers thickness also affects the sound-absorbing ability and generally speaking, the more centrally placed damping layer the higher the loss factor.


For suppression of flat surfaces in thicknesses of 2 mm is the “sandwich” technique superior to conventional single-sided bases. The technology is also suitable for damping of beams and profiles

For thinner materials suitable damping sheet type DS-2-S and insulating mats type ISM-75-S, BPL-35-S and BPL-75-S

For steel and aluminum structures, we recommend Swedac DG-U6 or VS-10 viskoeleastiskt materials. For wooden structures, we recommend Swedac Dämplim DG-A2