Fracture mechanics based approach to fatigue analysis of welded joints

Abstract Decades of operating experience related to welded T-joint connections in metallic structures have shown that fatigue cracks generally develop at welding due to both material heterogeneity (mismatch) and stress concentration. In the present paper, the fatigue behaviour of a metallic welded T-joint subjected to cyclic bending is analysed. A semi-elliptical surface crack is assumed to exist at the welding. The crack propagation is numerically examined by using the stress-intensity factor (SIF) values obtained from finite element analyses, and extensively presented in a recent work. Geometry and sizes of the welded T-joint are chosen in order to compare numerical results with experimental data available in literature, related to an actual welded joint of a common Francis turbine runner.

[1]  Hans-Jörg Huth,et al.  Fatigue Design of Hydraulic Turbine Runners , 2005 .

[2]  M. N. James,et al.  Design, manufacture and materials; their interaction and role in engineering failures , 2005 .

[3]  Jani Romanoff,et al.  On the slope of the fatigue resistance curve for laser stake-welded T-joints , 2013 .

[4]  Andrea Carpinteri,et al.  Shape change of surface cracks in round bars under cyclic axial loading , 1993 .

[5]  Andrea Carpinteri,et al.  Simplified analysis of fracture behaviour of a Francis hydraulic turbine runner blade , 2013 .

[6]  Bruno Atzori,et al.  The peak stress method combined with 3D finite element models for fatigue assessment of toe and root cracking in steel welded joints subjected to axial or bending loading , 2014 .

[7]  Liviu Marsavina,et al.  Methodology to assess integrity with application to collector copper lamellas , 2010 .

[8]  Bijayani Panda,et al.  Fatigue failure of weld joint of afterburner fuel manifold of a jet engine , 2013 .

[9]  Filippo Berto,et al.  Recent developments in brittle and quasi-brittle failure assessment of engineering materials by means of local approaches , 2014 .

[10]  R. D. Henshell,et al.  CRACK TIP FINITE ELEMENTS ARE UNNECESSARY , 1975 .

[11]  R. Barsoum,et al.  Further application of quadratic isoparametric finite elements to linear fracture mechanics of plate bending and general shells , 1975 .

[12]  Andrea Carpinteri,et al.  Sickle‐shaped surface crack in a notched round bar under cyclic tension and bending , 2009 .

[13]  Roberto Tovo,et al.  Developments of some explicit formulas useful to describe elastic stress fields ahead of notches in plates , 2002 .

[14]  F. J. Belzunce,et al.  Effect of mechanical mismatching on the ductile-to-brittle transition curve of welded joints , 2009 .

[15]  M Sick,et al.  Recent developments in the dynamic analysis of water turbines , 2009 .

[16]  Jaap Schijve,et al.  Fatigue of structures and materials , 2001 .

[17]  Lucjan Witek,et al.  Experimental crack propagation and failure analysis of the first stage compressor blade subjected to vibration , 2009 .

[18]  H. S. Khatak,et al.  Failure analysis of a T-joint of AISI type 316 L stainless steel , 2003 .

[19]  D. Radaj.  State-of-the-art review on the local strain energy density concept and its relation to the J-integral and peak stress method , 2015 .

[20]  Andrea Carpinteri,et al.  Notched shells with surface cracks under complex loading , 2006 .

[21]  Andrea Carpinteri,et al.  Notched double-curvature shells with cracks under pulsating internal pressure , 2009 .

[22]  D. Radaj,et al.  State‐of‐the‐art review on extended stress intensity factor concepts , 2014 .

[23]  P. C. Paris,et al.  A Critical Analysis of Crack Propagation Laws , 1963 .

[24]  Andrea Carpinteri,et al.  Fatigue growth of a surface crack in a welded T-joint , 2005 .

[25]  A. Cornec,et al.  The effect of yield strength mis-match on the fracture analysis of welded joints: slip-line field solutions for pure bending , 2000 .

[26]  A. Cornec,et al.  Plastic stress-strain fields and limit loads of a plane strain cracked tensile panel with a mismatched welded joint , 1997 .

[27]  Andrea Carpinteri,et al.  Influence of the cold-drawing process on fatigue crack growth of a V-notched round bar , 2010 .

[28]  Andrea Carpinteri,et al.  Circumferentially notched pipe with an external surface crack under complex loading , 2003 .

[29]  Sebastian Muntean,et al.  Failure analysis of a Francis turbine runner , 2010 .

[30]  Erik Åstrand,et al.  Fatigue life assessment of improved joints welded with alternative welding techniques , 2014 .

[31]  Reza Ghomashchi,et al.  Hydro turbine failure mechanisms: An overview , 2014 .