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TECHNICAL PAPERS

# A State-Switched Absorber Used for Vibration Control of Continuous Systems

[+] Author and Article Information
Mark H. Holdhusen

University of Wisconsin-Marathon County, 518 S 7th Ave., Wausau, WI 54401mholdhus@uwc.edu

Kenneth A. Cunefare

The George W. Woodruff School of Mechanical Engineering, The Georgia Institute of Technology, Atlanta, GA 30332-0405ken.cunefare@me.gatech.edu

J. Vib. Acoust 129(5), 577-589 (May 04, 2007) (13 pages) doi:10.1115/1.2748465 History: Received March 08, 2006; Revised May 04, 2007

## Abstract

A state-switched absorber (SSA) is a device that is capable of switching between discrete stiffnesses; thus, it is able to instantaneously switch between resonance frequencies. The state-switched absorber is essentially a passive vibration absorber between switch events; however, at each switch event the SSA instantly “retunes” its natural frequency and maintains that frequency until the next switch event. This paper considers the optimization of the state-switched absorber applied to a continuous vibrating system and details the experimental validation of these simulation results. A simulated annealing optimization algorithm was utilized to optimize the state-switched absorber. For the most part, the SSA performed only marginally better than a classical tuned vibration absorber (TVA). However, for a select few cases considered, the SSA was able to reduce the kinetic energy of the plate to which it is attached by $12.9dB$ over that of a classical tuned vibration absorber. The optimal SSA location on a clamped square plate was near the center of the plate for the vast majority of the forcing cases considered. To experimentally validate the simulation, a SSA was fabricated by employing magnetorheological elastomers to achieve a stiffness change. For several two-force component excitations, several tuning configurations of the SSA were applied and the kinetic energy of the system was found and optimized. As with the majority of the optimization cases, the experiments showed the SSA outperforming the TVA by only $2dB$. When comparing the observed results to those found via simulation, the simulations accurately predicted the performance of the SSA in the experiments.

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## Figures

Figure 1

Model of state-switched dynamical device

Figure 2

State-switched absorber attached to a plate, subject to multiharmonic point forcing

Figure 3

Kinetic energy ratio, in decibels, of an optimized SSA system to an untreated plate as function of two forcing frequencies

Figure 4

Kinetic energy ratio, in decibels, of an optimized SSA plate system to an optimized TVA plate system as a function of two forcing frequencies

Figure 5

Optimum SSA location in the x direction on the plate as function of two forcing frequencies

Figure 6

Optimum SSA location in the y direction on the plate as function of two forcing frequencies

Figure 7

Mean of two SSA tuning frequencies normalized by first mode of plate as function of two forcing frequencies

Figure 8

Ratio of optimum SSA tuning frequencies for a plate as function of two forcing frequencies

Figure 9

Kinetic energy ratio of SSA to optimized TVA as a function of tuning parameters near the best performing SSA

Figure 10

Kinetic energy ratio of SSA to optimized TVA as a function of tuning parameters near average performing SSA

Figure 11

MR elastomer implementation of a state-switched absorber

Figure 12

SSA resonance frequencies as a function of electromagnet current

Figure 13

Frequency response of plate

Figure 14

Experimental setup with sensors and actuators

Figure 15

Plate layout including accelerometers, force transducer, and SSA locations

Figure 16

Experimental kinetic energy ratio, in decibels, of the plate with SSA attached to untreated plate

Figure 17

Experimental kinetic energy ratio, in decibels, of a plate with SSA attached to a plate with TVA attached

## Errata

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