Vibration control by a variable damping and stiffness system with magnetorheological dampers

A vibration isolation system with variable damping and stiffness control is practical and has good performances. However, conventional devices of variable stiffness are usually complicated. A magnetorheological (MR) fluid damper only needs a small electric current to provide the magnetic field. It is easy to achieve variable damping with an MR damper in vibration systems. In this paper, two MR fluid dampers in series were used to achieve the variable damping and stiffness for the system. The passive, variable damping, variable stiffness, and variable damping and stiffness systems were investigated in experiment and theoretical calculation. The time and frequency responses to sinusoidal, sweep and random inputs showed that the system with a variable damping and stiffness had better properties.