Aluminum Weld Fatigue Calculation Curve Proposal


Updates: Feb 10, June 7-11 2011, Jan.2012

Copyright (C) 2011,2012 F.A. Conle and Univ. of Waterloo
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Introduction: Recent approaches in the prediction of fatigue life of welded
structures have used the concept of local "hot-spot" stress or
strain near the weld region of interest to quantify the magnitude
of the fatigue loading. Previous guidelines for bridges and other
structures incorporated a series of parallel fatigue life design S-N
curves, where each curve is a function of weld detail severity. The
local approach was implemented to overcome the difficulty of selecting
the weld severity type in complex geometry structures.

In the ground vehicle industry much of the local stress analysis is
done using elastic finite element (or simple stress*Kt) type calculations.
These elastic stresses are then transformed into local stresses and strains
using some form of Plasticity correction tool which requires a definition
of the cyclic stress-strain curve along with the fatigue life curve.
The analysis method proposed here allows this type of correction to be
made for aluminum weld data sets, and thus will conform to the standard
methods presently applied in the ground vehicle industry.

Digitizer used to create data sets: "engauge" works fairly well. Suggestion: Only digitize one "curve" at a time. Then restart the program for the next curve.

Other References for Hot-Spot Approach and Aluminum Welding:

  1. W. Schuetz and K.Winkler, "Betriebsfestigkeit geschweisster Schiffsaufbauten aus AlMg4,5Mn," (Fatigue strength of welded AlMg4.5Mn ship structures) Schiff und Hafen, v.21, N.9, Sept. 1969, pp.804-813.

  2. W. Sanders, "Fatigue Behavior of Aluminum Alloy Weldments," Fatigue of Aluminum Weld Res. Council Bulletin 171, 1972, pp.1-30.

  3. H.G. Köbler, "Beurteilung der Schwingfestigkeit von Schweissverbindungen aus AlZnMg1 auf dem Weg einer Oertlichen Dehnungsmessung (Teil 2), Aluminium, V.50, N.7, 1974, pp.445-449.

  4. W. Schuetz, "Zur Dimensionierung schwingbeanspruchter Aluminium-Schweissverbindungen," (On dimensioning welded aluminum joints subjected to cyclic loading) ZEV-Glas. Ann. 100, Nr.2/3 Feb/Mar, 1976, pp.41-45.

  5. D. Kosteas, I.Kirou, W.W.Sanders, "Fatigue Behaviour of Aluminum Alloy Weldments," Parts 1,2,3,4, Iowa State Univ. Rpes ISU-ERI-Ames-87028, Aug. 1986.

  6. G. Bhuyan and O.Vosikovsky, "Prediction of fatigue crack initiation lives for welded plate T-joints based on the local stress-strain approach," Int.J.Fatigue V.11 N.3, 1989, pp.153-159.

  7. NRIM Fatigue Data Sheet No.64, "Data Sheeets on Fatigue Properties for Butt Welded Joints of A5083P-O (Al-4.5Mg-0.6Mn) Aluminium Alloy Plates," Nat.Res.Inst.for Metals, Tokyo, 1990.

  8. T. Partanen and E.Niemi, "Hot Spot Stress Approach to Fatigue Strength Analysis of Welded Components: Fatigue Test Data fro Steel Plate Thicknesses up to 10mm," Fat. Frac. Engr. Mat. Struc., V.19 N.6, 1996, pp.709-722.

  9. J.L. Fayard, A.Bignonnet, K.Dang Van, "Fatigue Design Criterion for Welded Structures," Fat.Frac.Eng.Mat.Struc., V.19 N.6, 1996, pp.723-729.

  10. F.V. Lawrence, S.D.Dimitrakis, W.H.Munse, "The Variables Influencing the Fatigue Behavior of Structural Weldments," Submitted to ASM for inclusion in a Handbook. Jan. 1996. FCP Rep. No. 173/ UILU ENG-96-4001.
  11. M. Fermer, M.Andreasson and B.Frodin, "Fatigue Life Prediction of MAG- Welded Thin-Sheet Structures," SAE Paper 982311, SAE-P331, 1998.

  12. M. Backstrom and G.Marquis, "A review of multiaxial fatigue of weldments: experimental results, design code and critical plane approaches," Fat.Frac.Eng.Matl.Struc., V24, 2001, pp.279-291.

  13. J. Ahang, P.Dong, J.Hong, "EP1337942 Structural Stress Analysis," US Patent, 2002.

  14. O. Doerk, W.Fricke, and C.Weissenborn, "Comparison of different calculation method for structural stresses at welded joints," Int.J.Fatigue, v25 2003, pp.359-369.

  15. S.J. Maddox, "Review of fatigue assessment procedures for welded aluminium structures," Int.J.Fat. V25, 2003, pp.1359-1378.

  16. D. Kosteas and C.Radlbeck, "Static and Faigue Design of Aluminium Structures according to the new Eurocode 9," June 2004.

  17. BS7910:2005 British Standard for Welded Structures

  18. J.S. Crompton, "Fatigue Strength of Aluminum Alloy Welds," ASM Handbook Vol.19.

  19. P. Darcis, T.Lassen and N.Recho, "Fatigue Behavior of Welded Joints Part 2: Physical Modeling of the Fatigue Process," Welding Journal, Jan.2006, p.19s-26s.

  20. G. Glinka, S.M.Malik, J.Qian, Y.Tong, M.El-Zein, A.Popescu, "Stress Analysis and Fatigue of Weldments," Proc. of NAFEMS Vancouver, May22-25, 2007.

  21. M.L. Sharp, Behavior and Design of Aluminum Structures, McGraw Hill, 1972.
  22. R.C.Leever, "Application of Life Prediction Methods to As-Welded Steel Structures," ASME Int. Conf. on Advances in Life Prediction Methods, The Matls. Conf, Albany, NY, Apr. 18-20, 1983. Lib. of Congress 83-70330.