Active Mass Damper Demonstration for Ship Vibration Reduction

Modern naval vessels, which mount a large number of advanced electronic equipment, require such equipment to be well protected against external disturbance, including particularly vibration. The conventional means of minimising vibration is to increase structural rigidity, but this entails the increase of structural mass. If vibration could be suppressed by means of a lightweight compact device, it should immensely benefit naval vessel design. To this end, a two-axis active mass damper driven by a hydraulic actuator has been developed, which effectively reduces the vibration of ship superstructures. A prototype model damper unit has been tested in a laboratory, which proved to corroborate closely the high performance of the design estimated from simulated calculations. It is shown that; 1. The acceleration generated in the model structure by a sinusoidal exciting vibration was reduced to about 1/5 upon actuation of the device, and 2. A similar reduction of acceleration, to about 1/5, was obtained when the exciting vibration wave pattern reproduced the actual movement of a ship at sea.