D.H. Lammlein PhD Dissertation - Vanderbilt University

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Figure 71: 90° conical tool macrosections. Some 90°,Run2 welds were not macrosectioned. ................................................................................................................ 87 Figure 72: 90° conical tool macrosections. Note: Run 3, 1600rpm, 4ipm, 90° was macrosectioned twice. ....................................................................................................... 87 Figure 73: Run 1, 80° conical tool macrosections ............................................................ 88 Figure 74: Run 2, 80° conical tool macrosections ............................................................ 88 Figure 75: Run 3, 80° conical tool macrosections ............................................................ 89 Figure 76: Macrosection of the strongest conical weld (90°,1600rpm, 4ipm, Run#1). A minimal penetration ligament is crucial to weld strength. Failure in the tensile coupon occurred along the retreating (right) side weld nugget boundary. .................................... 89 Figure 77: Macrosection of the weakest 90° conical weld(90°,1400rpm, 4ipm, Run#1). Failure occurred at the jointline and along the retreating side weld nugget boundary. A significant lack of penetration (weld root) defect can be seen in this weld indicating a slight error in the automated zeroing process for this particular weld. Three welds at each parameter set were performed to distinguish such outliers. .............................................. 90 Figure 78: A particularly revealing macrosection (90°,1400rpm, 5ipm, Run#1). A jointline remnant can be seen curving through the weld nugget center. In addition, the lack of consolidation near the cone tip which is typical of a cone weld can be seen clearly here. The lack of sufficient probe surface area, heating, and pressure at the cone tip result in a lack of consolidation there. ........................................................................................ 90 Figure 79: (90º tool) Ultimate tensile strength of weld specimen over that of the parent plotted against spindle speed in rpm. Three welds were performed at each parameter set (ipm,rpm). ......................................................................................................................... 91 Figure 80: (80º tool) Ultimate tensile strength of weld specimen over that of the parent plotted against spindle speed in rpm. Three welds were performed at each parameter set (ipm,rpm). ......................................................................................................................... 91 Figure 81: (90º tool) Axial force magnitude for each weld plotted against spindle speed in rpm. Three welds were performed at each parameter set (ipm, rpm). 8000 N is typical x
for a similar conventional weld (3/4in. dia. shoulder, ½”-20 pin). Conical welds produce significantly lower axial force. ......................................................................................... 92 Figure 82: (90º tool) Weld moment for each weld plotted against spindle speed in rpm. Three welds were performed at each parameter set (ipm, rpm.) 18 N·m is typical for a similar conventional weld (3/4in. dia. shoulder, ½”-20 pin). Conical welds produce significantly lower weld moment...................................................................................... 92 Figure 83: (90º tool) Lateral force magnitude for each weld plotted against spindle speed in rpm. Three welds were performed at each parameter set (ipm, rpm). +2500 N Y is typical for a similar conventional weld (3/4in. dia. shoulder, ½”-20 pin). Conical welds produce significantly lower lateral force(change in sign due to clockwise vs. counterclockwise rotation). ........................................................................................................... 93 Figure 84: (90º tool) Longitudinal force magnitude for each weld plotted against spindle speed in rpm. Three welds were performed at each parameter set (ipm, rpm). +2500N X is typical for a similar conventional weld (3/4in. dia. shoulder, ½”-20 pin). Conical welds produce significantly lower longitudinal force. Sign for a particular weld is dependent to clockwise vs. counter-clockwise rotation. All conical welds in this experiment were made with clockwise rotation................................................................ 93 Figure 85: (80º tool) Axial force magnitude for each weld plotted against spindle speed in rpm. ................................................................................................................................... 94 Figure 86: (80º tool) Weld moment for each weld plotted against spindle speed in rpm. 94 Figure 87: (80º tool) Lateral force magnitude for each weld plotted against spindle speed in rpm. ............................................................................................................................... 95 Figure 88: (80º tool) Longitudinal force magnitude for each weld plotted against spindle speed in rpm. ..................................................................................................................... 95 Figure 89: Thermal camera data for 90º tool runs. .......................................................... 96 Figure 90: Thermal camera data for 80º tool runs. ........................................................... 96 Figure 91: CFD model geometry consisting of 510,299 tetrahedral elements. .............. 101 Figure 92: Increasing element refinement towards the weld interface. .......................... 101 xi
Page 1 and 2: FRICTION STIR WELDING OF SPHERES, C
Page 3 and 4: TABLE OF CONTENTS TABLE OF FIGURES
Page 5 and 6: Appendix ..........................
Page 7 and 8: Figure 16: Left(FE streamline), Mid
Page 9: Figure 51: A thermal camera image t
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 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 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
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
Page 127 and 128:
Figure 95: Lateral cross-section of
Page 129 and 130:
Figure 96: Attempts a probe tapered
Page 131 and 132:
CHAPTER IV THE FRICTION STIR WELDIN
Page 133 and 134:
applications for its high strength
Page 135 and 136:
Figure 97: Experimental weld sample
Page 137 and 138:
Figure 99: Split protrusion type de
Page 139 and 140:
with a cupped recess. It is however
Page 141 and 142:
of tapered retraction (i.e. move th
Page 143 and 144:
The adjustments in vertical positio
Page 145 and 146:
manners the assigned depth was main
Page 147 and 148:
Figure 108: Lateral macrosections f
Page 149 and 150:
Figure 110: (Supported, cupped tool
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
apparent strength of 26% parent whi
Page 157 and 158:
with a 100º conical tool (0.025”
Page 159 and 160:
Figure 119: Macrosection view of an
Page 161 and 162:
and tooling. Torque is highly depen
Page 163 and 164:
locally in proportion to the local
Page 165 and 166:
Figure 126: (threaded tool) Contour
Page 167 and 168:
Figure 128: (conical tool) Geometry
Page 169 and 170:
Figure 131: (threaded tool) Lateral
Page 171 and 172:
The results presented here show tha
Page 173 and 174:
Figure 136:(from left: Tapered retr
Page 175 and 176:
[8] Metallurgical analysis of ablat
Page 177 and 178:
CHAPTER V FRICTION STIR WELDING OF
Page 179 and 180:
Collaboration between Advanced Meta
Page 181 and 182:
eccentricity, the method of interio
Page 183 and 184:
gas tungsten arc welding of small d
Page 185 and 186:
Full penetration welds of 4.2” (1
Page 187 and 188:
Figure 143: The curvature of the pi
Page 189 and 190:
Figure 144: Experimental axial forc
Page 191 and 192:
Together, a fine wall thickness tol
Page 193 and 194:
Figure 147: Axial force history for
Page 195 and 196:
The weld macrosections show complet
Page 197 and 198:
Figure 154: Macrosections of welds
Page 199 and 200:
Figure 157: A thermal camera image
Page 201 and 202:
Figure 159: Average tool shank temp
Page 203 and 204:
471,146 faces. The meshes are fine
Page 205 and 206:
Figure 162: A closeup view of mesh
Page 207 and 208:
4 2 3 4 5 16 " 1.745 2 0.24
Page 209 and 210:
applied heat locally in proportion
Page 211 and 212:
Figure 164: Modeled temperature con
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Figure 172: Model pathlines for the
Page 219 and 220:
Figure 174: Model pathlines for the
Page 221 and 222:
later speed setting, the tool welds
Page 223 and 224:
Figure 178: Zoom view of a macro ta
Page 225 and 226:
Figure 180: The superficial appeara
Page 227 and 228:
Figure 182: The rotary welding appa
Page 229 and 230:
Figure 185: A diagram illustrating
Page 231 and 232:
CONCLUSION AND FUTURE WORK Conclusi
Page 233 and 234:
new FSW process environment is reso
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D.H. Lammlein PhD Dissertation - Vanderbilt University

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