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Deformation Analysis of Magnetic Elastomers using Finite Element Method

Norouzi, Faezeh | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 49542 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Naghdabadi, Reza; Sohrabpour, Saeed; Goudarzi, Taha
  7. Abstract:
  8. Magnetic elastomers are smart materials that consist of a combination of elastomeric matrix and magnetic particles. The mechanical and magnetic properties of this materials are changed by Applying an external magnetic field. The presence of an external magnetic field can cause these elastomers deform largely.Significant deformations of the magnetic elastomers, has made them suitable for a wide range of applications. The aim of this project is to solve the governing equations of magnetic elastomers with finite element method. Since there are no suitable models for the behavior of these elastomers in the commercial softwares, magnetic field module and solid mechanics module should be coupled by means of a proper model. In this thesis, a quasi-static model was considered in COMSOL Multiphysics to analyze the behavior of magnetic elastomers by using magnetic field and solid mechanics modules. In this model, Maxwell stress was applied to the surface of the body as an external load and the coupling between magnetic field and solid mechanics modules was stablished by this stress. The existing experimental results in the references was used for determining material coefficients. Then some boundary value problems including deformation of a cantilever beam in homogenous magnetic field, deformation of a cylinder in both homogenous and non-homogenous magnetic fields and deformation of a plate in homogenous magnetic field were solved. The results were validated with the existing results in the references. In addition deformation of a sphere in homogenous magnetic fields was solved. The bending of a cantilever beam in 0.01-0.04 T fields was studied. This bending is caused by rotation of particles in homogenous magnetic field. The results matche the experimental data for small displacements. For larger displacements and also higher intensity of the magnetic fields, the error between the results increases. Considering the magnetic field dependent properties, the errors for fields less than 0.04 T were under 5%. The length of a field-structural cylinder was increased after applying homogenous magnetic field to it. This extention is due to the magnetic force between particles. The model predicted the extention correctly in small fields (less than 0.05 T). For a slender cylinder in non- homogenous magnetic field, the extention was matched with the theoretical results with an error less than 3 percent. Applying the homogenous magnetic field to a plate such that the field and the normal vector form an angle, has led to bending before buckling. When the particles have identical orientation and the property functions are defined, the deformation caused by rotation of particles are predictable. Based on the validated results, the model predicts the deformations caused by the magnetic field gradient properly
  9. Keywords:
  10. Smart Materials ; Finite Element Method ; COMSOL Software ; Magnetorheological Elastomer(MRE) ; Magnetic Elastomers

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