D.H. Lammlein PhD Dissertation - Vanderbilt University

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Figure 34: A similar test using the tracked geometry (t=70s to t=130s). Substantial data was collected for the tracked configuration as this geometry proved useful for seam misalignment detection. For the tracked configuration welds, the axial force was shown to have the greatest change in magnitude with lateral offset, in addition to being several fold the largest process force in magnitude. The remaining process forces showed more complicated and less pronounced variations with lateral position and are thus neglected in this analysis. Fig. 5 shows data collected from 10 separate welds using the tracked geometry. Each point is represents a single weld and is the average axial force value over the steady state weld period where transient effects are minimal. 52
Figure 35: Experimental Welds, Axial force (1000xN) vs. lateral offset(in) for tracked configuration. The tracked configuration shows generally higher axial forces near the jointline. For effective seam misalignment detection, a substantive axial force trend must hold within a narrow range of offsets near the jointline. Relationships between lateral offset and the X, Y, and moment forces are believed to be secondary effects of the axial force variation combined with tool rotation and travel. Changes in the axial force with lateral offset can be attributed to changes in material geometry and composition below and in the vicinity of the shoulder. Imposed Axial Load FEA Analysis The following FEA analysis uses the same axial force applied to the tool for all cases and examines the subsequent material deflection beneath the shoulder with geometry and offset changes. By considering only axial force, the total number of elements in the offset models can be halved with a symmetry plane. A preliminary 53
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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 ..........................
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Figure 16: Left(FE streamline), Mid
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Figure 51: A thermal camera image t
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for a similar conventional weld (3/
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Figure 102: Tapered retraction proc
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setting are indicated. Note that st
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Unsupported welds of this kind with
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Figure 157: A thermal camera image
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ottom sample is a tungsten inert ga
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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 and 58: Figure 18: Temperature contour over
Page 59 and 60: Figure 22: Temperature distribution
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: Figure 33: Process forces and later
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
Page 111 and 112: Figure 71: 90° conical tool macros
Page 113 and 114: Figure 75: Run 3, 80° conical tool
Page 115 and 116: Figure 79: (90º tool) Ultimate ten
Page 117 and 118: Figure 83: (90º tool) Lateral forc
Page 119 and 120: Figure 87: (80º tool) Lateral forc
Page 121 and 122: The Eulerian, finite volume, CFD so
Page 123 and 124: Figure 92 shows the increasing elem
Page 125 and 126: 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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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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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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