Energy Dissipation of a Suspension-Type Tuned Mass Damper by Varying Pendulum Length

Energy Dissipation of a Suspension-Type Tuned Mass Damper by Varying Pendulum Length

In this paper, an optimal energy dissipation algorithm is proposed for a semi-active suspension-type tuned mass damper(SA-STMD) by varying the pendulum length. The SA-STMD mechanism consists of a mass block, a suspension rope, and a movable fulcrum. The fulcrum is similar to a short tube that is actuated by a linear motor on a track in a vertical direction. As the fulcrum goes up, the pendulum length extends and the stiffness of the SA-STMD decreases. On the other hand, as the fulcrum goes down, the pendulum length shortens and the stiffness of the SA-STMD increases. By varying the fulcrum position, the SA-STMD restoring force can be adjusted. When the energy dissipated by the suspension-type tuned mass damper(STMD) is insufficient, the stiffness of the SA-STMD varies according to the optimal energy dissipation algorithm to provide a controllable restoring force that is designed to act as a viscous damper that can make up the lack of dissipated energy. By numerical verification, the optimal energy dissipation algorithm can produce a variable restoring force with a hysteresis loop in a butterfly shape. Therefore, the SA-STMD using the optimal energy dissipation algorithm can supply enough damping to match the demand.