Variable Damping and Stiffness Suspension System with Two Controllable Dampers

摘要

Semi-active vibration systems expend a small amount of energy to change the system parameters such as damping and stiffness. The semi-active systems with variable damping and stiffness have demonstrated excellent performance. However, conventional devices for controlling variable stiffness are typically complicated and difficult to implement in most applications. To address this issue, a new configuration that requires two controllable dampers is proposed. A controllable damper and a constant spring comprise a Voigt element. The Voigt element and a spring are in series. The stiffness of the net system is changed by controlling the damper in the Voigt element, and the other damper provides variable damping for the system. The proposed system is experimentally implemented using two magnetorheological (MR) fluid dampers. This paper presents theoretical and experimental analyses of the proposed system. The experimental results agree well with the theoretical analyses. Five different control schemes involving low damping, high damping, damping on-off, stiffness on-off, and damping and stiffness on-off control are explored. The responses of the system to sinusoidal and random excitations show that the variable damping and stiffness control can be realized by the proposed system. Moreover, the system with damping and stiffness on-off control provides the best vibration isolation. To expand this work, a two degree-of-freedom suspension system is studied. The acceleration and relative displacement responses to sinusoidal, impulse and random excitations show that the system with damping and stiffness on-off has good performances.