Vibration Control by Magnetostrictive Actuator Coupled with Negative Inductance Circuits

Abstract

The stiffness of magnetostrictive materials can be controlled by the feedback action of the negative inductance circuits connected to the coils surrounding them. The effect is analogous to that of piezoelectric materials whose stiffness can be controlled by the negative capacitance circuits connected to them. The applied sinusoidal strain of the central rod in a magnetostrictive actuator induces the sinusoidal electric current in the surrounding coil. The current is increased or decreased by the feedback from the circuits, resulting in the corresponding increase or decrease in the strain under the fixed applied stress. The apparent dynamic elastic coefficient is thus arbitrarily controlled. If the actuator is placed between a shaker and a heavy mass, the resonant frequency of the system decreases or increases depending on the type of the negative inductance circuit. The transmissibility of vibration through the actuator is thus controlled in the respective frequency range.