D.H. Lammlein PhD Dissertation - Vanderbilt University

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[8] Pew JW, Nelson TW, Sorensen CD; Torque based weld power model for friction stir welding; Science and Technology of Welding and Joining,Vol.12, Num.4, p341, 2007. [9] Colegrove P, Painter M, Graham D, Miller T; 3 Dimensional flow and thermal modelling of the friction stir welding process; Proc. of the 2nd International Symposium on Friction Stir Welding, 2001. [10] Linder K, Khandahar Z, Khan J, Tang W, Reynolds AP; Rationalization of hardness distribution in alloy 7050 friction stir welds based on weld energy, weld power, and time/temperature history; Proc. of the 6 th International Symposium on Friction Stir Welding, 2007. [11] Dickerson TL, Shi Q-Y, Shercliff HR; Heat flow into friction stir welding tools; Proc. of the 4 th International Symposium on Friction Stir Welding, 2003. [12] Nunes A.C., Bernstien E.L., McClure J.C.: A rotating plug model for friction stir welding; Proc. of the 81 st American Welding Society Annual Convention, Chicago, IL, 2000. [13] St-Georges L, Dasylva-Raymond V, Kiss LI, Perron AL; Prediction of optimal parameters of friction stir welding: Proc. of the 6 th International Symposium on Friction Stir Welding, 2007. [14] Liechty B.C., Webb B.W., Modeling the frictional boundary conditions in friction stir welding: International Journal of Machine Tools & Manufacture, 2008, doi:10.1016/j.ijmachtools.2008.04.005 [15] Chao Y., Qi X., Heat Transfer in FSW: Experimental and Numerical Studies; Journal of Manufacturing Science and Engineering, February 2003, Vol. 125, 145 [16] R. Nandan, G. G. Roy and T. DebRoy, Numerical Simulation of Three Dimensional Heat Transfer and Plastic Flow during Friction Stir Welding of Aluminum Alloys, Metallurgical and Materials Transactions A, 2006, vol. 37A, pp. 1247-1259 [17] Fourment L., Guerdoux S., Numerical Simulation of the Friction Stir Welding Process using Lagrangian, Eulerian and ALE Approaches. Proceedings of the 5th International Friction Stir Welding Symposium, TWI, Metz, France (2004) 80
CHAPTER III THE APPLICATION OF SHOULDERLESS CONICAL TOOLS IN FRICTION STIR WELDING: AN EXPERIMENTAL AND THEORETICAL STUDY <strong>Lammlein</strong>, D. H., DeLapp, D.R., Fleming, P.A., Strauss, A.M., and Cook, G.E., “The application of shoulderless conical tools in friction stir welding: An experimental and theoretical study,” Materials and Design, 30 (2009), 4012-4022. Abstract A friction stir welding (FSW) tool geometry, consisting of a shoulderless conical probe, is investigated for application to closed contour welding, variable thickness welding, and open loop control welding. By use of a tapered retraction procedure and a ramped rotational velocity, a conical tool may facilitate material disengagement with minimal surface defects in applications that do not permit weld termination defects (e.g. pipes, pressure vessels, fuselages, nosecones). In addition, because the vertical position of the tool relative to the material surface is less critical with a conical tool than with other tool designs, it can be used in an open-loop fashion (i.e. without process force feedback control) and on materials whose thicknesses are highly variable. The use of a conical probe without a shoulder is not documented in the literature, and the aim of this work is to establish the conditions for mechanically sound welds. Effective tool geometries and process variables are found via experimental analysis. Thermal, tensile, macrosection, and process force data are presented along with a computational fluid dynamics (CFD) process model. It is concluded that this type of tooling is capable of producing acceptable welds when applied to butted aluminum plates and that similar methods would likely be effective in the applications described previously. Introduction 81
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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
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: Figure 65: Contour of velocity magn
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
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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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