Aluminum Welds: Local Stress/Strain Results

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 the method has been applied reasonably successfully to steel weldments. Thus far only a few investigations have been done to determine if a similar approach will work for aluminum welds. Given the emphasis on light weight fuel efficient vehicles, it would appear that our committee could collect available studies and suggest suitable life prediction methods in a short task force type effort.

Proposal for Fatigue Des. + Evaluation Comm.:
Develop Design Curves for Fatigue of Aluminum Weldments

  1. Collect papers and reports that utilize a local stress or strain to assess loading of aluminum welded samples or components. A begining is provided in the reference list below. Please send any others you can suggest.
    I believe that there are at least two data bases for weld fatigue results: One at UoIllinois, another supported by Kosteas in Muenchen. If anyone knows how to access these please let us know.

  2. Digitize the data and tabulate the files at this (or some other convienient web site) for all members to use. There is a digitization software (GNU license) available on the internet. http://sourceforge.net/projects/digitizer/ that works fairly well. Also others are available.

  3. Develop prediction methods. Question 1: Will a simple Neuber type Kt (as per R.C.Leever) approach work for aluminum weldments?

  4. Correlate with welded aluminum fatigue test results. A few variable amplitude tests perhaps? 


If you are interested in participating in this study please 
contact Dan Lingenfelser or Al Conle

Table of files to date:

  1. R.C.Leever's original presentation to FD+E
    also published in paper: 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.

  2. F.A.Conle Presentation: Summary and Proposal presented at Oct. 2010 F.D.+E. Meeting, Chrysler Tech. Center

  3. aa6061.csv file of AA 6061 Neuber Stress Plot from paper: F.A.Conle and J.J.F.Bonnen, Using the Neuber Plot to Account for the Effects of Scatter, Corrosion and Welding in Strain-Life Fatigue Test Data 2008 ISOPE Conf. Vancouver BC, July 10.

As more data sets or email suggestions are received we will post them here.

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. Koebler, "Beurteilung der Schwingfestigkeit von Schweissverbindungen aus AlZZnMg1 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 andE.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.