D.H. Lammlein PhD Dissertation - Vanderbilt University

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Lammlein, D. H., Longhurst, W. H., Delapp, D. R., Flemming, P. A., Strauss, A. M., & Cook, G. E. (2010). The Friction Stir Welding of Hemispheres – A technique for Manufacturing Hollow Spheres. Journal of Advanced Manufacturing . Longhurst, W. R. (2009). Dissertation: Force control in friction stir welding. Vanderbilt University. Longhurst, W. R., Strauss, A. M., & Cook, G. E. (2009). Enabling Automation of Friction Stir Welding: The Modulation of Weld Seam Input Energy by Traverse Speed Force Control. American Society of Mechanical Engineers Journal of Dynamic Systems Measurement and Control . Longhurst, W. R., Strauss, A. M., & Cook, G. E. (n.d.). Identification of the key enablers for force control of friction stir welding. American Society of Mechanical Engineers Journal of Manufacturing Science and Engineering , 2009. Longhurst, W. R., Strauss, A. M., Cook, G. E., & Fleming, P. A. (April 28, 2010). Torque control of friction stir welding for manufacturing and automation. International Journal of Advanced Manufacturing Technology . Longhurst, W. R., Strauss, A. M., Cook, G. E., Cox, C. D., Hendricks, C. E., & Gibson, B. T. (2010). Investigation of force controlled friction stir welding for manufacturing and automation. Proceedings of the Institution of Mechanical Engineers, Part B, Journal of Engineering Manufacturing., Volume 224 . Na, S. J., & Lee, H. J. A study on parameter optimization in the circumferential GTA welding of aluminium pipes using a semi-analytical. Journal of Materials Processing Technology; 57, 1996, 95- 102. Newell, W. F., Sperko, W. J., Mannings, D. C., Anderson, T., & Connell, D. D10 COMMITTEE ON PIPE AND TUBE WELDING. p32: American Welding Society. Packer, S. M., & Matsunaga, M. (2004). Friction Stir Welding Equipment and Method for Joining X65 Pipe. Proceedings of the 14th Intl. Offshore and Polar Eng. Conf. Toulon, France. Pew, J. W., Nelson, T. W., & Sorensen, C. D. (2007). Torque based weld power model for friction stir welding. Sci Technol Weld Join 12(4) , 341. Schmidt, H., Hattel, J., & Wert, J. (2004). An analytical model for the heat generation in friction stir welding. Modelling Simul. Mater. Sci. Eng. 12 , 143–157. Tello, K. E., Gerlich, A. P., & Mendez, P. F. Constants for hot deformation constitutive. Science and Technology of Welding and Joining; 2010, VOL 15, NO 3. Thomas, W. M. (1991). Friction stir butt welding. International Patent Application No PCT/GB92/02203. 206
CONCLUSION AND FUTURE WORK Conclusion The research presented is expected to expand the range of application of the FSW process. The use of force feedback control of weld seam alignment permits the use of FSW in an automated, manufacturing setting on blind type t-joints. Experimental and computational data demonstrated that the vertical member of the t-joint can be followed based on process force feedback. This will allow a FSW machine tool to follow ribs under large metal sheets without tedious alignment and tool path determination. In the case of serpentine ribs, this research will permit the application of FSW to a geometry which was previously not feasible. In this work, the FSW was shown for the first time to be capable of welding small diameter butted hemisphere type joints. It was shown that a cupped shoulder tool in conjunction with internal support can be used to effectively join two hemispheres at a high percentage of the parent material strength. Additionally, it was shown that for cases where internal support is not permissible that a conical type tool can be used to obtain welds exceeding 50% penetration. In a practical measure of strength where these partial penetration welds are compared to the strength of the full thickness of the parent material, these unsupported welds achieved strengths exceeding 25%. These strengths were achieved using the limited weld parameter permutations attempted experimentally and can likely be increased. A partial penetration weld of butted hemispheres without the use of an internal support has applications to external compression vessels. Additionally, the use of a conical tool in FSW at partial penetration without anvil support applies to other situations where the underside of the work is inaccessible and the use of an underside support device is unfeasible. The joining of butted hemispheres with full weld penetration was demonstrated successfully with weld strengths exceeding 70% over the limited parameter range tested. 207
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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
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INTRODUCTION Friction Stir Welding,
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educed conduction lengths. In small
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CHAPTER I LITERATURE REVIEW: COMPUT
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frictional condition at the interfa
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contact. The contact area can inclu
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For horizontal sections, a heat inp
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(1.11) where r p is the probe (pin)
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This efficiency term, η pd , is kn
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The heat input on the tool surface
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The added complication of these met
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Figure 5: Lateral cross sections of
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Flow stress in aluminum alloys is d
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Figure 8: Three flow fields a) rota
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and post-weld cool-down. This model
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Williams et al. [60] use a 2D-axisy
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Figure 16: Left(FE streamline), Mid
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Figure 18: Temperature contour over
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Figure 22: Temperature distribution
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Figure 24: Lateral velocity contour
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Figure 26: Experimental(white) vers
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Figure 28: Top view schematic of tu
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[5] Taylor RE, Groot H, Goerz T, Fe
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[41] Heinz B., Skrotzki B., Eggler
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CHAPTER II COMPUTATIONAL ANALYSIS O
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Figure 30: Blind t-joint setup with
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Figure 33: Process forces and later
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Figure 35: Experimental Welds, Axia
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Figure 37: FEA boundary conditions
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A 4500 N axial force is applied eve
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axial force with lateral offset dur
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Figure 42: Contour plot of von Mise
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Figure 44: Deformation contour for
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Figure 46: Quarter-plate model for
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Figure 49: Contour plot of deflecti
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where P is the weld power (W), Q is
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Figure 52: Fluent CFD model zones.
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Figure 55: Thermal contour of weld
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Figure 59: Thermal contour of weld
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Figure 61: Velocity vectors for 0.0
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Figure 65: Contour of velocity magn
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CHAPTER III THE APPLICATION OF SHOU
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Figure 66: A shoulder-less, conical
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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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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
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 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: Figure 185: A diagram illustrating
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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