Evaluation of S/N Diagram in Welded Joints Based on Different Fatigue Failure Criteria

Document Type: Original Article

Authors

Department of Mechanical Engineering, Khomeinishahr Branch, Islamic Azad University, Khomeinishahr/Isfahan, Iran

Abstract

One of the most important problems in the welded Joints is the low fatigue strength due to the residual stresses. Purpose of this study is to investigate the effect of residual stresses on S/N diagram of the welded joints. For this purpose, welding process of two plates is firstly modeled on a precise and three-dimensional model. This simulation has been carried out in two non-coupled thermal-mechanical steps, including the birth and death of elements technique, presence of molten flow inside melting pool and latent heat generated by phase transformations in the simulator program. Thermal and mechanical results of the program are compared with numerical and experimental results of other researchers, which indicates acceptable accuracy of the program. In the next step, effect of welding process residual stress on S/N diagram is investigated with two different fatigue criteria, which the results indicate a decrease in the fatigue strength. Goodman's modified fatigue criterion shows 88%, and Gerber's criterion shows 78% of reduction. Finally, by examining effect of changes in air flow parameters and preheating, the results showed that the transient air flow reduced fatigue strength for 5% and preheating, results in a 9% increase in fatigue strength.

Keywords


[1]     Marin, T., Nicoletto, G., Fatigue Design of Welded Joints using the Finite Element Method and the 2007 Asme Div. 2 Master Curve, Fracture and Structural Integrity, Vol. 3, No. 9, 2009, pp. 76–84.

[2]     Carpinteri, A., Spagnoli, A., and Vantadori, S., Multiaxial Fatigue Life Estimation in Welded Joints Using the Critical Plane Approach, International Journal of Fatigue, Vol. 31, No. 1, 2009, pp. 188–196.

[3]     Livieri, P., Lazzarin, P., Fatigue Strength of Steel and Aluminum Welded Joints Based on Generalized Stress Intensity Factors and Local Strain Energy Values, International Journal of Fracture, Vol. 133,No. 3, 2005, pp. 247–276.

[4]     Maddox, S. J., Fatigue Strength of Welded Structures: Woodhead publishing, 1991.

[5]     Kong, F., Ma, J., and Kovacevic, R., Numerical and Experimental Study of Thermally Induced Residual Stress in the Hybrid Laser–GMA Welding Process, Journal of Materials Processing Technology, Vol. 211, No. 6, 2011, pp. 1102–1111.

[6]     Chang, P. H., Teng, T. L., Numerical and Experimental Investigations On the Residual Stresses of The Butt-Welded Joints, Computational Materials Science, Vol. 29, No. 4, 2004, pp. 511–522.

[7]     Messler, R. W., Principles of Welding: Processes, Physics, Chemistry, and Metallurgy: John Wiley & Sons, 2008.

[8]     Asadi, M., Goldak, J. A., Nielsen, J., Zhou, J., Tchernov, S., and Downey, D., Analysis of Predicted Residual Stress in a Weld and Comparison with Experimental Data Using Regression Model, Int J Mech Mater Des, No. 5, 2009, pp. 353–364.

[9]     Bruder, T., Störzel, K., Baumgartner, J., and Hanselka, H., Evaluation of Nominal and Local Stress Based Approaches for the Fatigue Assessment of Seam Welds, International Journal of Fatigue, Vol. 34, No. 1, 2012, pp. 86-102.

[10]  Bokesjö, M., Al-Emrani, M., and Svensson, T., Fatigue Strength of Fillet Welds Subjected to Multi-Axial Stresses, International Journal of Fatigue, Vol. 44, 2012, pp. 21–31.

[11]  BS7608, Code of Practice for Fatigue Design aand Assessment of Steel Structures: British Standards Institution, 1993.

[12]  Hobbacher, A., Recommendations for Fatigue Design of Welded Joints and Components: OH: Welding Research Council Shaker Heights, 2009.

[13]  Sonsino, C. M., Overview of the State of the Art On Multiaxial Fatigue of Welds, European Structural Integrity Society, Vol. 25, 1999, pp. 195–217.

[14]  Sonsino, C. M., Multiaxial Fatigue Assessment of Welded Joints–Recommendations for Design Codes, International Journal of Fatigue, Vol. 31, No. 1, 2009, pp. 173–187.

[15]  Bae, D., Sohn, I., and Hong, J., Assessing the Effects of Residual Stresses On the Fatigue Strength of Spot Welds, Welding Journal, Vol. 82, 2003, pp. 18–23.

[16]  Krasovsky, S., Sonnichsen, S., and Bachmann, D., On the Residual Stresses in Multi- Pass Welds: Coupling of Welding Simulation and Fatigue Analysis, Procedia Engineering, Vol. 10, 2011, pp. 506- 511.

[17]  Socie, D., Marquis, G., Multiaxial Fatigue: Warrendale, Society of Automotive Engineers Inc, 2000.

[18]  Vasantharaja, P., Maduraimuthu, V., Vasudevan, M., and Palanichamy, P., Assessment of Residual Stresses and Distortion in Stainless Steel Weld Joints, Materials and Manufacturing Processes, Vol. 27, No. 12, 2012, pp. 1376– 1381.

[19]  Yuguang, C., Zhanbin, M., Shihua, Z., and Haiqing, T., FEM Study On the Stress Concentrationfactors of K-Joints with Welding Residual Stress, Applied Ocean Research, Vol. 43, 2013, pp. 195–205.

[20]  Ganesh, K., Vasudevan, M., Balasubramanian, K., Chandrasekhar, N., and Vasantharaja, P., Thermo-Mechanical Analysis of TIG Welding of AISI 316 LN Stainless Steel, Materials and Manufacturing Processes, Vol. 29, No. 8, 2014, pp. 903– 909.

[21]  Vasantharaja, P., Vasudevan, M., and Palanichamy, P., Effect of Welding Processes On the Residual Stress and Distortion in Type 316LN Stainless Steel Weld Joints, Journal of Manufacturing Processes, Vol. 19, 2014, pp. 187- 193.

[22]  Bhatti, A. A., Barsoum, Z., Murakawa, H., and Barsoum, I., Influence of Thermo-Mechanical Material Properties of Different Steel Grades On Welding Residual Stresses and Angular Distortion, Materials and Design, Vol. 65, 2015, pp. 878–889.

[23]  Lopez-Jauregi, A., Esnaola, J. A., Ulacia, I., Urrutibeascoa, I., and Madariaga, A., Fatigue Analysis of Multipass Welded Joints Considering Residual Stresses, International Journal of Fatigue, Vol. 79, 2015, pp. 75- 85.

[24]  Lopez-Jauregi, A., Ulacia, I., Esnaola, J. A., Ugarte, D., and Torca, I., Procedure to Predict Residual Stress Pattern in Spray Transfer Multipass Welding, the International Journal of Advanced Manufacturing Technology, Vol. 76, No. 9-12, 2014, pp. 2117-2129.

[25]  Wang, D., Zhang, H., Gong, B., and Deng, C., Residual Stress Effects On Fatigue Behaviour of Welded T-Joint: A Finite Fracture Mechanics Approach, Materials and Design, Vol. 91, 2016, pp. 211- 217.

[26]  Forouzan, M. R., Heidari, A., and Golestaneh, S. J., FE Simulation of Submerged arc Welding of API 5L-X70 Straight Seam Oil and Gas Pipes, Journal of Computational Methods in Engineering (ESTEGHLAL), Vol. 28, No. 1, 2009, pp. 93-110.

[27]  Forouzan, M. R., MirfalahNasiri, S. M., Mokhtari, A., Heidari, A., and Golestaneh, S. J., Residual Stress Prediction in Submerged arc Welded Spiral Pipes, Materials & Design, Vol. 33, 2012, pp. 384-394.