Vibration Isolation and Reduction by Theory of Variable Structure Systems.

Abstract

By controlling spring stiffness, vibration isolation and reduction of the one-degree-of freedom system are achieved in this study. The control algorithm of the spring stiffness is based on the variable structure system (VSS) theory, and the theory is developed to consider the spring stiffness limitation and delay of switching time. The stiffness-variable spring is realized by a straight bar which is hinged to the mass at right angles to the direction of mass motion, and the axial force is applied at the end of the bar. The axial force causes restoring force equivalent to the spring, and the stiffness is varied by controlling the axial force. In the numerical simulations and experiments, the settling time of the impulse response and the displacement transmissibility are investigated. The results show that this system is effective in suppressing shock motion and isolating vibration transmitted from the floor.