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Modeling and Vibration Analysis of Laminated Composite Beam with Magneto-Rheological Fluid Segments

Naji, Jalil | 2017

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  1. Type of Document: Ph.D. Dissertation
  2. Language: English
  3. Document No: 49533 (58)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Behzad, Mehdi; Zabihollah, Abolghasem; Shamloo, Amir
  7. Abstract:
  8. Magnetorheological (MR) materials show variations in their rheological properties when subjected to varying magnetic fields. They have quick time response, in the order of milliseconds, and thus are potentially applicable to structures and devices when a tunable system response is required. When integrated with a structural system, they can produce higher variations in the dynamic response of the structure. In this thesis, vibration behavior of laminated-composite beam with MR Fluid is investigated.In most studies, shear strain across the thickness of MR layer has been considered as a constant value which does not precisely describe the actual shear strain field. Shear modulus of MR layer in structure is dramatically lower than the elastic layers, leading to higher shear deformation inside the MR layer, thus, classical theories are not accurate enough to predict the dynamic behavior of such structures. In present thesis a layerwise displacement theory has been utilized to predict a more accurate deformation field for MR-composite beam and the equations of motion are derived using finite element model (FEM).
    Knowing complex shear modulus of MR fluid is essential for analysis of dynamic behavior of MR structures. When subjected to magnetic field, rheology of MR fluid is changed, it is needed to find a relation between complex shear modulus and the magnetic field intensity. In this study, standard test ASTM E756-98 is employed to evaluate the complex shear modulus of MR fluid. Through experimental tests, a practical formulation for complex shear modulus of MR fluid is presented. In this formulation, shear modulus of MR fluid is used as function of magnetic flux density and also driving frequency.The influence of MR fluid in MR-beam allows for control of vibration by active control of magnetic field. In this research, a control strategy is proposed for vibration suppression of MR-beams. Using the concept of switched stiffness, a semi-active vibration control algorithm is designed. The control objective here is to suppress the vibration transients in the system in the presence of the excitation and disturbances. In order to validate the presented finite element formulation and extract vibration characteristics of MR-beam, an experimental setup is prepared. In order to investigate every aspect of MR-beam, several samples of MR-beam with different materials and dimensions are used. The comparison between the numerical and experimental results shows good agreement
  9. Keywords:
  10. Flow Behavior ; Vibration Control ; Laminated Composite Beam ; Magnetorheological (MR)Fluid ; Shear Modulus ; Interlaminar Stress ; Complex Shear Modulus

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