PSI - Issue 31

79 5

N.D. Bibbo et al. / Procedia Structural Integrity 31 (2021) 75–79 N. D. Bibbo et al. / Structural Integrity Procedia 00 (2019) 0 0–000

a)

b)

Fig. 3. Findley vs MWCM fatigue failure estimations. In a) Findley no. of cycles to failure calculated vs experimental no. cycles to failure and in b) similar plot for MWCM. 7. Conclusion The notch stress method was used in conjunction with the Findley and Modified Wöhler Curve Methods for assessing fatigue failure on a large set of welded joints found in the literature subjected to bending, torsion, proportional and non-proportional loadings. The fatigue predictions obtained from the Findley and MWCM criterions where compared to experimental results shown in literature. Based on the results comparing Findley and MWCM vs experimental data show that, generally the MWCM method provides the best results, as fewer non-conservative fatigue predictions are seen. References Gough, H. J., and Pollard, H. V., 1935. The strength of metals under combined alternating stresses. Proceedings of the Institution of Mechanical Engineers, 131(1), pp. 3-103. Findley, W., 1956. Fatigue of metals under combinations of stress. Cover carries title: Theories relating to fatigue of materials under combination of stress. Technical report no. 2 on basic research on fatigue failures under combined stress. Susmel, L., and Tovo, R., 2011. Estimating fatigue damage under variable amplitude multiaxial fatigue loading. Fatigue and Fracture of Engineering Materials and Structures, 34(12), pp. 1053 – 1077. Hobbacher, A. F., 2016. Recommendations for Fatigue Design of Welded Joints and Components, 2nd ed. Springer. Bäckström M., 2003. Multiaxial fatigue life assessment of welds based on nominal and hot spot stresses. Ph.D. thesis. Laapeenranta University, Finland. Siljander OA, Kurath P, Lawrence FV., 1991. Nonproportional biaxial fatigue of welded joints. UILU-ENG no. 158, University of Illinois. Sonsino CM., 1995. Multiaxial fatigue of welded joints under in-phase and out-of phase local strains and stresses. Int J Fatigue, 55–70. Witt M, Zenner H., 1997. Multiaxial fatigue behaviour of welded flange-tube connections under combined loading. experiments and lifetime calculation. In: 5th International conference on biaxial/multiaxial fatigue and fracture, Cracow, Poland, p. 421–34. Amstutz H, Störzel K, Seeger T., 2001. Fatigue crack growth of a welded tube-flange connection under bending and torsional loading. Fatigue Fract Eng Mater Struct, 357–68. Yousefi F, Witt M, Zenner H., 2001. Fatigue strength of welded joints under multiaxial loading: experiments and calculations. Fatigue Fract Eng Mater Struct, 339–55. Pedersen, M., 2016. Multiaxial fatigue assessment of welded joints using the notch stress approach. International Journal of Fatigue, 83, 269 – 279. Bruun, Ø. & Härkegård, G., 2015. A comparative study of design code criteria for prediction of the fatigue limit under in-phase and out-of-phase tension–torsion cycles. International Journal of Fatigue; 73, 1 – 16. Susmel, L., 2014. Four stress analysis strategies to use the modified wöhler curve method to perform the fatigue assessment of weldments subjected to constant and variable amplitude multiaxial fatigue loading. International Journal of Fatigue, 67, pp. 38 – 54 Sonsino, C., Fricke, W., de. Bruyne, F., Hoppe, A., Ahmadi, A., and Zhang, G., 2012. Notch stress concepts for the fatigue assessment of welded joints – background and applications. International Journal of Fatigue, 34(1), pp. 2 – 16. Hobbacher, A. F., 2016. Recommendations for Fatigue Design of Welded Joints and Components, 2nd ed. Springer. Sonsino, C. M., 2008. Suggested allowable equivalent stresses for fatigue design of welded joints according to the notch stress concept with the reference radii rref=1.00 and 0.05mm. International Institute of Welding.