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Swept Spot Integral Fasteners

[pdf presentation file]

  •  Technology
    • Integral fasteners
    • Fabrication in place (using parent material)
    • Solid-state mechanical stirring process
    • Circumscribed friction stir welding
    • Fine equiaxed grain structure
    • Continuous stress path through joint
    • Tailorable configurations & sizes
  • Potential Benefit
    • Discrete joints
    • Pad-up versus stack-up at joint location
    • Tailored joint sizes – not limited by knife-edge condition
    • Tailored shapes (e.g. circular, elliptical, arced, etc.)
    • Reduction in loose debris (from drilling holes)
    • Potential reduction in interaction between contiguous fasteners
    • Rapid installation and reduced cycle time
    • Simplified fixturing requirements (compared to linear FSW)
    • Potential installation via robots versus FSW machines
    • Distortion control options (e.g. random sequence of installation)
    • Discontinuous heat affected zone (HAZ) along joint line
    • Favorable compressive residual stresses around discrete joint
    • Continuous (uninterrupted) electrical path at joint
    • Compatible with sealants on the faying surface
  • History
    • Circumscribing FSW – “Squircle”
    • Introduced by Addison and Robelou
    • Reference:  A. C. Addison and A. J. Robelou, “Friction Stir Spot Welding: Principle Parameters and Their Effects,” in Proceedings of the 5th International FSW Symposium, Metz, France, 2004
  • Specification Coverage
    • ISO/DIS 18785: Friction stir spot welding — Aluminiun
      • Part 1: Vocabulary
      • Part 2: Design of weld joints
      • Part 3: Qualification of welding operators
      • Part 4: Specification and qualification of welding procedures
      • Part 5: Quality and inspection requirements
  • Design Data
    • Propose Method
      • Evaluate as Installed Fasteners
      • Develop tables of static design minimums
    • Comparable to MMPDS Design Values
  • End Effectors
    • “End effector for forming swept friction stir spot welds”
    • Designed for robotic application, but may be used in any suitable mechanical delivery system
    • Patents
      • US 8,444,040
      • US 9,132,504
  • Stirbits®
    • Key Tool Features
      • Counterflow™ probe features (Patent US 7,942,306)
      • Mandrel™ probe configuration (Patent US 8,579,180)
      • TurboTip™ probe tip
    • Shoulder
      • Wiper™ shoulder configuration (Patent US 8,016,179)
  • Selected References
    1. A. C. Addison and A. J. Robelou, “Friction Stir Spot Welding: Principle Parameters and Their Effects,” in Proceedings of the 5th International FSW Symposium, Metz, France, 2004
    2. D. A. Burford, C. A. Widener and B. M. Tweedy, “Advances in Friction Stir Welding for Aerospace Applications,” in 6th AIAA Aviation Technology Integration and Operations Conference (ATIO), Wichita, Kansas, 2006
    3. B. M. Tweedy, S. Sellmeyer, A. Jahn and D. A. Burford, “Static Strength Comparison of Riveted versus Friction Stir Welded Stiffened Panels,” in 47th AIAA-ASME-ASCE-AHS-ASC Structures, Structural Dynamics, and Materials Conference, Newport, Rhode Island, 2006
    4. J. Merry, B. Tweedy, C. Widener and D. Burford, “Static Strength Comparison of Discontinuous Friction Stir Welded Stiffened Panels,” in 7th AIAA Aviation Technology, Integration and Operations Conference (ATIO), Belfast, Northern Ireland, September 18-20, 2007
    5. B. M. Tweedy, C. A. Widener and D. A. Burford, “The Effect of Surface Treatments on the Faying Surface of Friction Stir Spot Welds,” in Friction Stir Welding and Processing IV, Orlando, Florida, 2007
    6. J. Brown, C. A. Widener, G. Moore, K. Poston and D. A. Burford, “Evaluation of Swept Friction Stir Spot Welding in Al 2219-T6,” in Friction Stir Welding & Processing V, San Francisco, California, 2009
    7. J. Brown, C. Widener, D. Burford, B. Tweedy, W. Horn and G. Talia, “Evaluation of Swept Friction Stir Spot Welding Through Sealants and Surface Treatments,” in 8th International Conference on Trends in Welding Research Conference, Callaway Gardens Resort Pine Mountain, Georgia, 2008
    8. J. Brown, D. A. Burford, C. A. Widener, W. Horn, J. Talia and B. M. Tweedy, “Corrosion and Fatigue Evaluation of Swept Friction Stir Spot Welding through Sealants and Surface Treatments,” in Friction Stir Welding & Processing V, San Francisco, California, 2009
    9. D. A. Burford, B. M. Tweedy and C. A. Widener, “Fatigue Crack Growth in Integrally Stiffened Panels Joined Using Friction Stir Welding and Swept Friction Stir Spot Welding,” Journal of ASTM International, vol. 5, no. 4, p. Online Publication, 2008
    10. D. A. Burford, B. M. Tweedy and C. A. Widener, “Development of Design Data for FSW and FSSW,” in 7th International Friction Stir Welding Symposium, Awaji Island, Japan, 20-22 May 2008
    11. B. M. Tweedy, C. A. Widener, S. F. Jurak and D. A. Burford, “Effects of Weld Tool Design and Welding Parameters on Swept Friction Stir Spot Welding in Thin Gage Aluminum,” in 7th International Friction Stir Welding Symposium, Awaji Island, Japan, 2008
    12. B. M. Tweedy, C. A. Widener, J. Merry, J. Brown and D. A. Burford, “Factors Affecting the Properties of Swept Friction Stir Spot Welds,” in SAE 2008 World Congress, Detroit, Michigan, 2008
    13. T. J. Lam, C. A. Widener, J. Brown and D. A. Burford, “Low Z-Force Friction Stir Spot Welds Conventional Tool & Process Development Approach,” in Friction Stir Welding & Processing V, San Francisco, California, 2009
    14. J. Brown, J. Gross, J. Buller and D. Burford, “Retractable vs. Fixed Probe Tools in Swept Friction Stir Spot Welding,” in Friction Stir Welding & Processing IV, San Diego, California, 2011
    15. K. Witthar, J. Brown and D. Burford, “Swept FSSW in Aluminum Alloys through Sealants and Surface Treatments,” in Friction Stir Welding and Processing VI, TMS Annual Meeting & Exhibition, February 27 – March 3, 2011, San Diego, CA, 2011
    16. A. V. Iyer, “Effect of tool shoulder geometry on the axial force and mechanical strength of FSSW aerospace alloys AA7075 and AA2024,” WSU, Wichita, KS, 2012
    17. M. Awang, A. Ismail and Z. M. A. K., “The Effects of Process Parameters on the Strength of Swept Friction Stir Spot Welded Plates,” in 10th International Friction Stir Welding Symposium (10FSWS), China National Convention Center, Beijing China, 2014
    18. Z.-M. Su, R.-Y. He, P.-C. Lin and K. Dong, “Fatigue analyses for swept friction stir spot welds in lap-shear specimens of alclad 2024-T3 aluminum sheets,” International Journal of Fatigue, vol. Volume 61, p. 129–140, 2014
    19. Khalid Nor and Dwight Burford, TWI Technical Literature Review 23973, http://www.twi-global.com/what-we-do/research-and-innovation/core-research-programme/technical-literature-reviews/process-capability-study-for-friction-stir-spot-welding-fssw/
    20. Mokhtar Awang, Azman Ismail, M. Aiman K. Zaman, “Effect of Process Parameters on the Strength of Swept Friction Stir Spot Welded Plates,” Machining, Joining and Modifications of Advanced Materials, Volume 61 of the series Advanced Structured Materials, 2016, pp 105-110