Vibration Damping

Vibrations may be caused by machinery, external forces, such as wind and waves, and the use and occupancy of a structure. The control of structural vibrations is important for human comfort, noise control and structural fatigue.

The SPS elastomer core is a natural damping component and provides an effective vibration-damping layer that is superior to conventional all-steel stiffened plate construction. Characteristic forced and free vibration tests indicate that the damping ratio of SPS plate structures is four times that of comparable stiffened steel structures. SPS plates provide equivalent damping to a concrete slab but without the excessive weight penalty. Concrete is four times heavier than SPS.

As SPS structures have a high natural frequency and a high damping ratio, these factors prevent resonance build-up and give low accelerations at the likely input frequencies for human use, such as crowds at sports and music events. Through damping sound at source, the use of SPS reduces the need for acoustical insulation. Therefore the reduction of structural or ship borne noise is achieved without the added weight, costs or fabrication complexity of traditional coatings.

Images illustrate:
Fig 1 Characteristic forced and free vibration test
Fig 2SPS deck plate in structural borne noise testing facility