Experimental Vibration Control of a Two-Degree of Freedom, State-Switched Absorber System

Abstract

A State-Switched Absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as compared to classical tuned vibration absorbers for vibration control. Previous theoretical simulations show that for a system subjected to a multi-harmonic disturbance, using an appropriate logic for switching states, the SSA reduces vibration more effectively than classical tuned vibration absorbers (TVA). This paper considers the experimental performance of the SSA for vibration suppression of an elastically mounted lumped mass base. State switching is achieved using magneto-rheological fluid to connect or disconnect a coil spring in parallel with other coil springs. The stiffness state is controlled by applying or removing a magnetic field across of the MR fluid. Experiments were performed over a range of forcing and tuning frequencies. The SSA system, optimally tuned, outperformed the optimal classical TVA system for all combinations of forcing frequencies.

Investigation of the Two-state, Maximum Work Extraction Switching Rule of a State-switched Absorber for Vibration Control

“…The fundamental question is whether or not to switch at a zero strain switch opportunity. For the work previously done by Cunefare et al (2000) and Holdhusen and Cunefare (2002), a maximum work extraction principle was implemented. To achieve a maximum work extraction in a two state SSA, the switching rule is…”

“…A state-switched absorber is a mass-spring-damper device attached to a vibrating base where the spring is capable of instantaneously changing its stiffness, thus the absorber can instantaneously switch its resonance frequency. Through proper switching, the SSA can reduce vibrations in the base to which it is attached better than can classical devices (Cunefare et al, 2000;Holdhusen and Cunefare, 2002). The state-switched absorber is a derivative of the classical tuned vibration absorber (TVA) (Den Hartog, 1956).…”

“…The SSA did as well as or better than a classical TVA at controlling the lumped mass-spring-damper system to which it was attached for all combinations of excitation frequencies investigated. Holdhusen and Cunefare (2002) examined the experimental validation of the state-switched absorber used for this simple two-degree of freedom system. The SSA showed performance gains experimentally as compared to classical tuned vibration absorbers.…”

Optimization of location and tuning of the state-switched absorber for controlling beam vibration

“…With proper switching logic, the SSA has improved performance in vibration control as compared to classical passive devices, especially when the excitation contains more than one frequency component. 2,3 Much research has been conducted on the use of vibration absorbers with variable dynamic properties for reducing structural vibrations. Davis,et al 4 used the dependence of piezoceramic's stiffness on its termination impedance to create a variable stiffness element.…”