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Magneto-sensitive rubber in the audible frequency range
KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering, Marcus Wallenberg Laboratory MWL. KTH, School of Engineering Sciences (SCI), Aeronautical and Vehicle Engineering.
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 [en]
Magneto-sensitivity, Rubber, Audible frequency range, Amplitude dependence, Vibration isolator, Fletcher-Gent effect, Stiffness
National Category
Fluid Mechanics and Acoustics
Identifiers
URN: urn:nbn:se:kth:diva-4024ISBN: 91-7178-392-X (print)OAI: oai:DiVA.org:kth-4024DiVA: diva2:10445
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
List of papers
1. Amplitude and frequency dependence of magneto-sensitive rubber in a wide frequency range
Open this publication in new window or tab >>Amplitude and frequency dependence of magneto-sensitive rubber in a wide frequency range
2005 (English)In: Polymer testing, ISSN 0142-9418, E-ISSN 1873-2348, Vol. 24, no 5, 656-662 p.Article in journal (Refereed) Published
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. In order to illustrate these two features, results are presented of measurements performed in the audible frequency range on two different kinds of rubber: silicone and natural rubber with a respective iron particle volume concentration of 33%. The particles used are of irregular shape and randomly distributed within the rubber. An external magnetic field of 0-0.8 T is applied. Both kinds of rubber are found to be strongly amplitude dependent and, furthermore, displaying large responses to externally applied magnetic fields - a maximum of 115%. Also included are graphs of measurements on silicone and natural rubber devoid of iron particles. Those results support the conclusion that introducing iron particles in the rubber gives rise to a strong, non-negligible, amplitude dependence in the entire frequency range.

Place, publisher, year, edition, pages
Elsevier, 2005
Keyword
magneto-sensitivity, Fletcher-Gent effect, rubber, amplitude dependence, audible frequency range
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-5907 (URN)10.1016/j.polymertesting.2005.04.001 (DOI)000229979000018 ()2-s2.0-19144365921 (Scopus ID)
Note

QC 20100816

QC 20151208

Available from: 2006-06-01 Created: 2006-06-01 Last updated: 2015-12-09Bibliographically approved
2. Smart audio frequency energy flow control by magneto-sensitive rubber isolators
Open this publication in new window or tab >>Smart audio frequency energy flow control by magneto-sensitive rubber isolators
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.

Keyword
magnetorheological elastomers, dependence
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-5909 (URN)10.1088/0964-1726/17/1/015043 (DOI)000254176200044 ()2-s2.0-41849110916 (Scopus ID)
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
3. Magneto-sensitive rubber in a noise reduction context: exploring the potential
Open this publication in new window or tab >>Magneto-sensitive rubber in a noise reduction context: exploring the potential
2005 (English)In: Plastics, rubber and composites, ISSN 1465-8011, E-ISSN 1743-2898, Vol. 34, no 8, 365-371 p.Article in journal (Refereed) Published
Abstract [en]

In a noise reduction context, magneto-sensitive (MS) rubber is likely to become a. reality in the very near future. This conclusion is reached from the following: a review of the rapidly growing literature on the subject, a discussion around experimentally obtained data on magneto-sensitive rubber, and finally a computer simulation of a MS rubber isolator which seeks to illustrate the utility and great potential of this smart material within the audible frequency range. In contrast to normal rubber, magneto-sensitive rubber contains small iron particles that respond to externally applied magnetic fields, consequently altering the mechanical properties of the rubber. This response increases for small strains strengthening further the link to structure-borne sound applications where displacement amplitudes are usually small; this is borne out by vibration measurements in a running car engine, included for the purpose of placing experimental data on MS rubber in a real context.

Keyword
magneto-sensitive rubber, noise, audible frequency range, magnetorheological elastomers, dependence
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-15244 (URN)10.1179/174328905x59692 (DOI)000233871700005 ()2-s2.0-28744444327 (Scopus ID)
Note

QC 20150721

Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2017-12-12Bibliographically approved
4. A non-linear constitutive audio frequency magneto-sensitive rubber model including amplitude, frequency and magnetic field dependence.
Open this publication in new window or tab >>A non-linear constitutive audio frequency magneto-sensitive rubber model including amplitude, frequency and magnetic field dependence.
2011 (English)In: Journal of Sound and Vibration, ISSN 0022-460X, E-ISSN 1095-8568, Vol. 330, no 5, 947-954 p.Article in journal (Refereed) Published
Abstract [en]

A novel constitutive model of magneto-sensitive rubber in the audible frequency range is presented. Characteristics inherent to magneto-sensitive rubber within this dynamic regime are defined: magnetic sensitivity, amplitude dependence, elasticity and viscoelasticity. Prior to creating the model assumptions based on experimental observations concerning these components are formulated. The first observation is that not only does the rubber display a strong amplitude dependence even for small strains, but also the magnetic sensitivity is strongly amplitude dependent. The second and third are, respectively, that the elastic component is magneto-sensitive, whereas the viscoelastic dependence on magnetic induction appears to be small. Thus, the model is developed from these assumptions and parameters are optimized with respect to experimental values for one case and subsequently validated for others; a very good agreement is obtained.

Place, publisher, year, edition, pages
Elsevier, 2011
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-5910 (URN)10.1016/j.jsv.2010.09.010 (DOI)000286700100007 ()2-s2.0-78649449082 (Scopus ID)
Funder
Swedish Research Council, 621-2002-5643TrenOp, Transport Research Environment with Novel Perspectives
Note

QC 20100816

Available from: 2006-06-01 Created: 2006-06-01 Last updated: 2016-04-28Bibliographically approved
5. The frequency, amplitude and magnetic field dependent torsional stiffness of a magneto-sensitive rubber bushing
Open this publication in new window or tab >>The frequency, amplitude and magnetic field dependent torsional stiffness of a magneto-sensitive rubber bushing
2011 (English)In: International Journal of Mechanical Sciences, ISSN 0020-7403, E-ISSN 1879-2162, Vol. 60, no 1, 54-58 p.Article in journal (Refereed) Published
Abstract [en]

A dynamic torsional stiffness model of a magneto-sensitive circular annular rubber bushing is presented where influences of frequency, amplitude and magnetic field dependence are included. This is achieved by employing a newly developed non-linear magneto-sensitive audio frequency constitutive equation in an engineering formula for the torsional stiffness of a rubber bushing. The engineering stiffness formula predicts the frequency and amplitude dependent stiffness in a simple way, based on geometric dimensions and the shear modulus. The shear modulus is provided by the rubber model. The results from these calculations predict and clearly display the possibility of controlling over a large frequency range, through the application of a magnetic field, the magneto-sensitive rubber bushing stiffness.

Keyword
audio frequency, magneto-sensitive, non-linear, rubber isolator
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-5911 (URN)10.1016/j.ijmecsci.2012.04.006 (DOI)000305598400006 ()2-s2.0-84861850196 (Scopus ID)
Funder
Swedish Research Council, 621-2002-5643
Note
QC 20120719Available from: 2006-06-01 Created: 2006-06-01 Last updated: 2012-07-19Bibliographically approved

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