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Smart audio frequency energy flow control by magneto-sensitive rubber isolators
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, MWL Structural and vibroacoustics.ORCID iD: 0000-0001-5760-3919
2008 (English)In: Smart materials and structures (Print), ISSN 0964-1726, E-ISSN 1361-665X, Vol. 17, no 1Article in journal (Refereed) Published
Abstract [en]

A magneto-sensitive rubber isolator inserted between a source and an infinite plate is modelled in the audible frequency range, and the energy flow into the plate with the rubber subjected to a magnetic field applied perpendicular to the axial displacement is calculated. Subsequently the result is compared to the corresponding energy flow for zero magnetic induction; upon the application of an external magnetic field the rubber becomes stiffer, thus shifting the internal resonances of the isolator. This is a fast and reversible process enabling adaption of the isolator to rapidly changing audio frequency conditions by simply turning on and off a magnetic field. In the application example considered, the energy flow into the plate at the first internal dynamic peak stiffness frequency is reduced by approximately 7 dB-a large difference in a sound and vibration context-by inducing magnetic saturation of the rubber.

Place, publisher, year, edition, pages
2008. Vol. 17, no 1
Keyword [en]
magnetorheological elastomers, dependence
National Category
Applied Mechanics
Identifiers
URN: urn:nbn:se:kth:diva-5909DOI: 10.1088/0964-1726/17/1/015043ISI: 000254176200044Scopus ID: 2-s2.0-41849110916OAI: oai:DiVA.org:kth-5909DiVA: diva2:10442
Note

Uppdaterad från submitted till published. QC 20100816

QC 20150728

Available from: 2006-06-01 Created: 2006-06-01 Last updated: 2015-07-28Bibliographically approved
In thesis
1. Magneto-sensitive rubber in the audible frequency range
Open this publication in new window or tab >>Magneto-sensitive rubber in the audible frequency range
2006 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber is the focus of this thesis consisting of five papers A-E. Paper A presents results drawn from experiments on samples subjected to different constant shear strains over varying frequencies and magnetic fields. Main features observed are the existence of an amplitude dependence of the shear modulus referred to as the Fletcher-Gent effect for even small displacements, and the appearance of large MS effects. These results are subsequently used in Paper B and C to model two magneto-sensitive rubber isolators, serving to demonstrate how, effectively, by means of MS rubber, these can be readily improved. The first model calculates the transfer stiffness of a torsionally excited isolator, and the second one, the energy flow into the foundation for a bushing inserted between a vibrating mass and an infinite plate. In both examples, notable improvements in isolation are obtainable. Paper D presents a non-linear constitutive model of MS rubber in the audible frequency range. Characteristics inherent to magneto-sensitive rubber within this dynamic regime are defined: magnetic sensitivity, amplitude dependence, elasticity and viscoelasticity. A very good agreement with experimental values is obtained. In Paper E, the magneto-sensitive rubber bushing stiffness for varying degrees of magnetization is predicted by incorporating the non-linear magneto-sensitive audio frequency rubber model developed in Paper D, into an effective engineering formula for the torsional stiffness of a rubber bushing. The results predict, and clearly display, the possibility of controlling over a large range through the application of a magnetic field, the magneto-sensitive rubber bushing stiffness.

Place, publisher, year, edition, pages
Stockholm: KTH, 2006
Series
Trita-AVE, ISSN 1651-7660 ; 2006:37
Keyword
Magneto-sensitivity, Rubber, Audible frequency range, Amplitude dependence, Vibration isolator, Fletcher-Gent effect, Stiffness
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-4024 (URN)91-7178-392-X (ISBN)
Public defence
2006-06-14, F3, F, Lindstedtsvägen 26, KTH, 13:00
Opponent
Supervisors
Note
QC 20100816Available from: 2006-06-01 Created: 2006-06-01 Last updated: 2010-11-24Bibliographically approved
2. Exploring the vibration control potential of magneto-sensitive rubber
Open this publication in new window or tab >>Exploring the vibration control potential of magneto-sensitive rubber
2005 (English)Licentiate thesis, comprehensive summary (Other scientific)
Abstract [en]

Two new aspects of the dynamic behaviour in the audible frequency range of magneto-sensitive (MS) rubber are highlighted: the existence of an amplitude dependence of the shear modulus—referred to as the Fletcher–Gent effect—for even small displacements, and the appearance of large MS effects. These results have been obtained experimentally and are subsequently used to model two examples of magneto-sensitive rubber isolators to show how by means of MS rubber they can be improved. The first model calculates the transfer stiffness of a torsionally excited isolator and the second one the energy flow into the foundation for a bushing inserted between a vibrating mass and an infinite plate. In both examples notable improvements in isolation can be obtained

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. 23 p.
Series
Trita-AVE, ISSN 1651-7660 ; 2005:18
Keyword
Applied mechanics, magneto-sensitive rubber, Teknisk mekanik
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-241 (URN)
Presentation
2005-05-26, MWL 74, Farkost o Flyg, Teknikringen 8c, Stockholm, 18:00
Opponent
Supervisors
Note
QC 20101125Available from: 2005-05-31 Created: 2005-05-31 Last updated: 2010-11-25Bibliographically approved

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