A study of a hybrid damper using a lever-type displacement magnifying mechanism, giant magnetostrictive actuators and rare-earth magnets

In previous papers, the authors proposed two types of passive dampers using a lever-type displacement magnifying mechanism. One is a magnetic damper using rare-earth magnets and the other is a viscoelastic-friction damper using acrylic viscoelastic material. In this paper, a new type of hybrid damper using a lever-type displacement magnifying mechanism, giant magnetostrictive actuators and rare-earth magnets is proposed. The hybrid damper generates controllable friction force together with magnetic damping force which acts as a fail-safe mechanism in case of control system trouble, and is suitable for vibration in the region of amplitude 0.1∼10 mm. The trial damper was made and the resisting force characteristics were measured. The seismic responses of a three-dimensional piping system supported by the damper were measured using an electrohydraulic type shaking table. The experimental results are compared with the calculated results obtained by the finite element method (ANSYS), and the effects of vibration suppression of the hybrid damper are discussed. Moreover, these experimental and calculated results are compared with those obtained for a semiactive friction damper (which is one removed the rare-earth magnets from the hybrid damper) and a passive magnetic damper (which is one removed the giant magnetostrictive actuators from the hybrid damper).