Title:
Tunability and sensitivity investigation of MREs in longitudinal vibration absorbers

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dc.contributor.advisor Cunefare, Kenneth A.
dc.contributor.author Lerner, Anne-Marie Albanese en_US
dc.contributor.committeeMember Lynch, Christopher S.
dc.contributor.committeeMember Massimo Ruzzene
dc.contributor.committeeMember Sadegh, Nader
dc.contributor.committeeMember Reginald DesRoches
dc.contributor.department Mechanical Engineering en_US
dc.date.accessioned 2009-01-22T15:45:20Z
dc.date.available 2009-01-22T15:45:20Z
dc.date.issued 2008-08-20 en_US
dc.description.abstract Broadband, variable, and random excitations are often suppressed using active vibration absorbers (AVAs). While AVAs can be effective, they also are expensive and subject to instability when the disturbance is ill defined. A state-switched absorber (SSA) can be used for these same vibration classes while reducing the expense and instability because an SSA is only allowed to be active at discrete instances. SSAs are spring-mass-damper devices in which at least one element is controllably variable. The work presented in this dissertation evaluates the properties of magnetorheological elastomers (MREs) to assess their use in SSAs as variable springs. MREs are elastomers doped with magnetically permeable material, generally iron. They are modeled as lossy springs, and have stiffness and loss factor components. Natural frequency and stiffness behavior, and their relationships to static displacement, iron content, and forcing frequency and amplitude were determined. Loss factors were found to be independent of MRE content, configuration, and static displacement. This was confirmation that MREs are in fact controllable springs. Natural frequencies changed in the presence of magnetic fields by as much as 360%. The corresponding change in static displacement could not account for this frequency change. Transient data was found by determining the length of time it took for an MRE to achieve quasi-steady state oscillation behavior when subjected to a harmonic excitation. This time was referred to as the characteristic response time. The characteristic response time correlated to the ratio of the forcing frequency to the zero-field natural frequency. When a magnetic field was turned on, the characteristic response time on average was found to be consistently longer than when the magnetic field was turned off, regardless of iron content or configuration. The difference between these two characteristic response times is caused by the particles' mechanics. To form a chain, a magnetic field must both be set up, and particles must move to join together. When a chain is broken, the magnetic field must merely be removed. However, this difference gives opportunities for future research to be conducted on controlling MREs' transient responses. en_US
dc.description.degree Ph.D. en_US
dc.identifier.uri http://hdl.handle.net/1853/26553
dc.publisher Georgia Institute of Technology en_US
dc.subject Vibration en_US
dc.subject Absorbers en_US
dc.subject MREs en_US
dc.subject Smart materials en_US
dc.subject.lcsh Damping (Mechanics)
dc.subject.lcsh Vibration
dc.subject.lcsh Automatic control
dc.subject.lcsh Elastomers Magnetic properties
dc.title Tunability and sensitivity investigation of MREs in longitudinal vibration absorbers en_US
dc.type Text
dc.type.genre Dissertation
dspace.entity.type Publication
local.contributor.corporatename George W. Woodruff School of Mechanical Engineering
local.contributor.corporatename College of Engineering
relation.isOrgUnitOfPublication c01ff908-c25f-439b-bf10-a074ed886bb7
relation.isOrgUnitOfPublication 7c022d60-21d5-497c-b552-95e489a06569
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