Dynamic Shear Response of Magneto-active Elastomer to an Oscillatory Magnetic Field Input

Open Access
Kloss, Ryan Matthew
Area of Honors:
Mechanical Engineering
Bachelor of Science
Document Type:
Thesis Supervisors:
  • Paris R Vonlockette, Thesis Supervisor
  • Hosam Kadry Fathy, Honors Advisor
  • Magneto-active Elastomers
  • MAE
  • magnetorheological effect
  • dynamic response
  • magneto-mechanics.
Magneto-active and magnetorheological elastomers are defined, in simplest terms, as a rubber matrix filled with magnetic particles in order to affect the properties of the material by the interactions between the magnetized particles and the application of an external field. While much is known about the magnetorheological (MR) properties of magnetically filled elastomers, the property of a magneto-active elastomer (MAE) to actuate based on the alignment of its constituent particles remains incompletely investigated. The MR effect is a result of increased shear stiffening when the soft magnetic filler particles of an MRE are exposed to a magnetic field. Only recently has the use of hard magnetic filler to produce reversible deformation of a sample been investigated in MAEs. Researchers have determined the necessary alignments of particles and sample compositions to produce this deformation in a shear mode. While the shear actuation of an MAE patch in response to a sinusoidally applied field has been observed, this dynamic response of the MAE has not been fully characterized and the relationship between applied field and displacement amplitude has not been determined. In this study, MAE patches in a shear mass-spring-damper configuration were subjected to inputs from a magnetic field and the displacement of the patch was observed. Analysis of the data demonstrates the correlation between applied field strength and frequency and the responsive behavior of the MAE material. Displacement decays as a function of frequency, however this is most likely due to the decrease of the external field as it decays due to increased system electromagnetic impedance. The maximum displacement amplitude observed was 15.13 μm at a frequency of 0.25 Hz. The amplitude of the internal forcing function was shown to proportional to H^(3/2) with an α coefficient value in the forcing function equal to 7.991 x 10-3 N/mT^3/2, leading to a maximum experimental displacement of 9.90 μm.