Title Page
Abstract
Contents
Chapter 1. Introduction 12
1.1. Research Background 12
1.2. Contributions and Organization 15
Chapter 2. Magnetorheological Fluid 17
2.1. Overview of MRF 17
2.2. Proposal of New Type MRF Device 20
Chapter 3. Characteristics of Electromagnetic 22
3.1. Permanent Magnet 22
3.2. Electromagnet 24
Chapter 4. Simulations of MRF Device 28
4.1. Magnetostatic Analysis 28
4.2. MRF Analysis 45
4.3. Fluid-Structure Interaction 51
Chapter 5. Experimental Verifications 67
5.1. MRF Cushion Device 67
5.2. MRF Pressure Control Valve 68
5.3. Experimental Apparatus 69
5.4. Experimental Results 71
Chapter 6. Conclusions 93
6.1. MRF Cylinder Cushion Device 93
6.2. MRF Pressure Control Valve 94
References 96
요약 107
Table 3.1. Parameters of the permanent magnet 24
Table 3.2. Design parameters of the MRF valves 27
Fig. 2.1. Cluster formation of the MRF 17
Fig. 2.2. Stress characteristics of MR fluid 18
Fig. 2.3. Basic operating modes of MRF 19
Fig. 2.4. Concept of MRF cushion device 20
Fig. 2.5. Concept of MRF pressure control valve 20
Fig. 3.1. Directions of magnetization 23
Fig. 3.2. Magnetic hysteresis curve 23
Fig. 3.3. Concept of electromagnet 25
Fig. 4.1. B-H and relative permeability curve of MRF 132DG (Lord Co.) 31
Fig. 4.2. B-H and relative permeability curve of SM45C 32
Fig. 4.3. Boundary conditions for magnetostatic analysis of MRF cylinder cushion device 34
Fig. 4.4. Mesh model for magnetostatic analysis of MRF fluid cylinder cushion device 35
Fig. 4.5. Magnetic flux density contour plot of permanent magnet 36
Fig. 4.6. Surface plot of magnetic field distribution 36
Fig. 4.7. Streamline of magnetic flux line 37
Fig. 4.8. Variation of the magnetic flux density with the distance from the magnet (Point plot) 37
Fig. 4.9. Variation of the magnetic flux density with the distance from the magnet (Line plot) 38
Fig. 4.10. Variation of the magnetic flux density with the distance from the magnet 39
Fig. 4.11. Variation of the magnetic flux density with the distance from the magnet (line plot) 40
Fig. 4.12. Dimensions of electromagnet for the MR fluid pressure control valve device 40
Fig. 4.13. Boundary conditions for magnetostatic analysis of MR cylinder cushion device 41
Fig. 4.14. Mesh model for magnetostatic analysis of MR fluid pressure control valve device 41
Fig. 4.15. Magnetic flux density of electromagnet 42
Fig. 4.16. Magnetic flux density of electromagnet by distance from magnet 43
Fig. 4.17. Magnetic field distribution of electromagnet 44
Fig. 4.18. Magnetic flux density of field distribution of electromagnet 44
Fig. 4.19. Shear strain rate vs. Shear stress of MRF-132DG 49
Fig. 4.20. Shear strain rate vs. viscosity coefficient of MRF-132DG 49
Fig. 4.21. Calculation flow chart of Fluid-Structure Interaction 52
Fig. 4.22. Yield stress of MRF (132-DG) 54
Fig. 4.23. Magnetic field intensity on the surface of magnet of MRF cylinder cushion device 54
Fig. 4.24. Total friction force of MRF cylinder cushion device 55
Fig. 4.25. Total friction force of MRF pressure control valve device 55
Fig. 4.26. Yield shearing stress by gap distance 56
Fig. 4.27. Slider displacement by external pressure 57
Fig. 4.28. Slider velocity by external displacement 58
Fig. 4.29. Magnetic field intensity on the surface of electromagnet of MRF pressure valve 60
Fig. 4.30. Yield shear stress (1mm gap) according to applied current 60
Fig. 4.31. Yield shear stress by gap distance in case of applying a 2A of current 62
Fig. 4.32. Displacement by external pressure and applied current 63
Fig. 4.33. Displacement by external pressure and applied current 64
Fig. 4.34. Velocity by external pressure and applied current 65
Fig. 5.1. MRF cylinder cushion device 67
Fig. 5.2. MRF pressure control valve 68
Fig. 5.3. MRF cylinder cushion device setup 69
Fig. 5.4. MRF pressure control valve experimental apparatus setup 70
Fig. 5.5. Displacement and velocity analysis and comparison among experiment results 72
Fig. 5.6. Displacement and velocity analysis and comparison among experiment results 73
Fig. 5.7. Displacement and velocity analysis and comparison among experiment results 74
Fig. 5.8. Slider displacement and force characteristic by external pressure 76
Fig. 5.9. Slider displacement and force characteristic by external pressure 77
Fig. 5.10. Electric current output value of electromagnet according to applied voltage 77
Fig. 5.11. Displacement of poppet (1mm gap) 78
Fig. 5.12. Displacement of poppet (1mm gap) 79
Fig. 5.13. Displacement of poppet (2mm gap) 80
Fig. 5.14. Displacement of poppet (2mm gap) 81
Fig. 5.15. Exit pressure according to displacement of poppet (1mm gap) 83
Fig. 5.16. Exit pressure according to displacement of poppet (1mm gap) 84
Fig. 5.17. Exit pressure according to displacement of poppet (2mm gap) 85
Fig. 5.18. Exit pressure according to displacement of poppet (2mm gap) 86
Fig. 5.19. Displacement of poppet and velocity by external pressure 87
Fig. 5.20. Displacement of poppet and velocity by external pressure 88
Fig. 5.21. Displacement of poppet and velocity by external pressure 89
Fig. 5.22 A. comparison among experimental results and an analysis according to each external pressure and electromagnet input voltage 91
Fig. 5.23 A. comparison among experimental results and an analysis according to each external pressure and electromagnet input voltage 92