D.H. Lammlein PhD Dissertation - Vanderbilt University

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Figure 20: Modeled temperature distributions without considering tool rotation, figure from [63]. Temperature contours produced by Song and Kovacevic [64] using identical parameters and similar process forces using a different CFD model are presented for comparison: Figure 21: Modeled temperature distributions without considering tool rotation, figure from [64]. It is noted in [63] that CFD models presented in [63] and [64] achieve similar results. St.Georges et al. [64] goes on to present temperature contours with consideration for tool rotation: 34
Figure 22: Temperature distribution with consideration of tool rotation, figure from [64]. De Vuyst et al. [65] use MORFEO finite element software and an Eulerian formulation with mixed velocity-pressure discretization for the fluid flow. A the work material is modeled with a visco-plastic fluid law. Empirical studies of embedded copper foil and wire marker material are used for model validation. A simplification of the Norton-Hoff material law is used: 1 s 2 K ( 3 ε ) m − ε = & & Norton-Hoff Material Law where m=1 results in a Newtonian fluid of viscosity K, s is viscosity, and ε& is the strain rate. For this model, K and m are chosen as constant values averaged over the full temperature range. This results in a weak coupling between the flow and temperature fields. The temperature field is dependent only on viscous dissipation and thus on the flow field. The flow field is however independent of temperature in this model. The authors have a supercomputer available to them (28 Intel Itanium 2 processors with 2GB per processor RAM memory and 1.4TB available disk space) and 35
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FRICTION STIR WELDING OF SPHERES, C
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TABLE OF CONTENTS TABLE OF FIGURES
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Appendix ..........................
Page 7 and 8: Figure 16: Left(FE streamline), Mid
Page 9 and 10: Figure 51: A thermal camera image t
Page 11 and 12: for a similar conventional weld (3/
Page 13 and 14: Figure 102: Tapered retraction proc
Page 15 and 16: setting are indicated. Note that st
Page 17 and 18: Unsupported welds of this kind with
Page 19 and 20: Figure 157: A thermal camera image
Page 21 and 22: ottom sample is a tungsten inert ga
Page 23 and 24: N - newton (force unit) n - visco-p
Page 25 and 26: INTRODUCTION Friction Stir Welding,
Page 27 and 28: educed conduction lengths. In small
Page 29 and 30: CHAPTER I LITERATURE REVIEW: COMPUT
Page 31 and 32: frictional condition at the interfa
Page 33 and 34: contact. The contact area can inclu
Page 35 and 36: For horizontal sections, a heat inp
Page 37 and 38: (1.11) where r p is the probe (pin)
Page 39 and 40: This efficiency term, η pd , is kn
Page 41 and 42: The heat input on the tool surface
Page 43 and 44: The added complication of these met
Page 45 and 46: Figure 5: Lateral cross sections of
Page 47 and 48: Flow stress in aluminum alloys is d
Page 49 and 50: Figure 8: Three flow fields a) rota
Page 51 and 52: and post-weld cool-down. This model
Page 53 and 54: Williams et al. [60] use a 2D-axisy
Page 55 and 56: Figure 16: Left(FE streamline), Mid
Page 57: Figure 18: Temperature contour over
Page 61 and 62: Figure 24: Lateral velocity contour
Page 63 and 64: Figure 26: Experimental(white) vers
Page 65 and 66: Figure 28: Top view schematic of tu
Page 67 and 68: [5] Taylor RE, Groot H, Goerz T, Fe
Page 69 and 70: [41] Heinz B., Skrotzki B., Eggler
Page 71 and 72: CHAPTER II COMPUTATIONAL ANALYSIS O
Page 73 and 74: Figure 30: Blind t-joint setup with
Page 75 and 76: Figure 33: Process forces and later
Page 77 and 78: Figure 35: Experimental Welds, Axia
Page 79 and 80: Figure 37: FEA boundary conditions
Page 81 and 82: A 4500 N axial force is applied eve
Page 83 and 84: axial force with lateral offset dur
Page 85 and 86: Figure 42: Contour plot of von Mise
Page 87 and 88: Figure 44: Deformation contour for
Page 89 and 90: Figure 46: Quarter-plate model for
Page 91 and 92: Figure 49: Contour plot of deflecti
Page 93 and 94: where P is the weld power (W), Q is
Page 95 and 96: Figure 52: Fluent CFD model zones.
Page 97 and 98: Figure 55: Thermal contour of weld
Page 99 and 100: Figure 59: Thermal contour of weld
Page 101 and 102: Figure 61: Velocity vectors for 0.0
Page 103 and 104: Figure 65: Contour of velocity magn
Page 105 and 106: CHAPTER III THE APPLICATION OF SHOU
Page 107 and 108: Figure 66: A shoulder-less, conical
Page 109 and 110:
Figure 68: Typical axial(Z-axis) fo
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Figure 71: 90° conical tool macros
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Figure 75: Run 3, 80° conical tool
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Figure 79: (90º tool) Ultimate ten
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Figure 83: (90º tool) Lateral forc
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Figure 87: (80º tool) Lateral forc
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The Eulerian, finite volume, CFD so
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Figure 92 shows the increasing elem
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Figure 91: CFD model geometry consi
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Figure 95: Lateral cross-section of
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Figure 96: Attempts a probe tapered
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CHAPTER IV THE FRICTION STIR WELDIN
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applications for its high strength
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Figure 97: Experimental weld sample
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Figure 99: Split protrusion type de
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with a cupped recess. It is however
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of tapered retraction (i.e. move th
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The adjustments in vertical positio
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manners the assigned depth was main
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Figure 108: Lateral macrosections f
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Figure 110: (Supported, cupped tool
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Page 153 and 154:
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apparent strength of 26% parent whi
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with a 100º conical tool (0.025”
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Figure 119: Macrosection view of an
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and tooling. Torque is highly depen
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locally in proportion to the local
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Figure 126: (threaded tool) Contour
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Figure 128: (conical tool) Geometry
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Figure 131: (threaded tool) Lateral
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The results presented here show tha
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Figure 136:(from left: Tapered retr
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[8] Metallurgical analysis of ablat
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CHAPTER V FRICTION STIR WELDING OF
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Collaboration between Advanced Meta
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eccentricity, the method of interio
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gas tungsten arc welding of small d
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Full penetration welds of 4.2” (1
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Figure 143: The curvature of the pi
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Figure 144: Experimental axial forc
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Together, a fine wall thickness tol
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Figure 147: Axial force history for
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The weld macrosections show complet
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Figure 154: Macrosections of welds
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Figure 157: A thermal camera image
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Figure 159: Average tool shank temp
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471,146 faces. The meshes are fine
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Figure 162: A closeup view of mesh
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4 2 3 4 5 16 " 1.745 2 0.24
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applied heat locally in proportion
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Figure 164: Modeled temperature con
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Page 217 and 218:
Figure 172: Model pathlines for the
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Figure 174: Model pathlines for the
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later speed setting, the tool welds
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Figure 178: Zoom view of a macro ta
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Figure 180: The superficial appeara
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Figure 182: The rotary welding appa
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Figure 185: A diagram illustrating
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CONCLUSION AND FUTURE WORK Conclusi
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new FSW process environment is reso
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D.H. Lammlein PhD Dissertation - Vanderbilt University

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