Two semi-active approaches for vibration isolation: piezoelectric friction damper and magnetorheological damper

Two different approaches to perform vibration isolation control on a single-degree-of-freedom system using semiactive dampers are investigated. In the first approach, the friction damper consists of an actuator, which is based on a piezoelectric stack with a mechanical amplifying mechanism that provides symmetric forces within the isolator. The advantages of such an actuator are its high bandwidth, displacement response and its ability to operate in vacuum environments such as in space. The damper is constrained to move using an air bearing that produces a virtually ideal single-degree-of-freedom spring-mass system. Within this work, the actuating ability of the friction-based actuator is characterized. The relationship between the force generated by the actuator and the applied voltage was found to be linear. In the second approach, a magnetorheological (MR) fluid damper is designed and fabricated. This damper is ideal for use in a semi-active control system where the damping characteristics can be adjusted by varying the amount of current applied to the damper.