A simplified fatigue assessment method for high quality welded cruciform joints

Abstract The primary goal of this study was to develop an equation relating the geometric parameters to fatigue strength which can be used is routine design assessment. To attain this, the influence of local geometrical weld variations on the fatigue strength of non-load-carrying cruciform fillet welded joints were systematically studied using plane strain linear elastic fracture mechanics (LEFM). The effects of weld toe radius, flank angle and weld size were considered. Both continuous weld toe cracks and semi-elliptical toe cracks with alternate pre-existing defect depths were considered. A previously developed experimental crack aspect ratio development curve was used for assessing the growth of the semi-elliptical cracks using 2D FE models. A total of 152 experimental fatigue data points from six published studies of welded cruciform joints were evaluated. Details of the actual weld toe radius, flank angle and weld size were available for these joints. For the high quality welds evaluated, an assumed initial crack depth of 0.05 mm was found to correlate best with the experimental data. Of all the geometric parameters considered analytically, weld toe radius was found to have the most dramatic influence on fatigue life. A simple equation is proposed which relates welded joint fatigue strength to the ratio weld toe radius/plate thickness for high quality welds.

[1]  Torgeir Moan,et al.  Probabilistic analysis of the uncertainty in the fatigue capacity of welded joints , 1983 .

[2]  Chanakya Arya,et al.  Eurocode 3: Design of steel structures , 2018, Design of Structural Elements.

[3]  Hans-Peter Günther,et al.  Erhöhung der Ermüdungsfestigkeit von geschweißten höherfesten Baustählen durch Anwendung von Nachbehandlungsverfahren , 2005 .

[4]  T. Nykänen,et al.  Fatigue analysis of non-load-carrying fillet welded cruciform joints , 2007 .

[5]  Yves Verreman,et al.  Fatigue notch factor and short crack propagation , 2008 .

[6]  S. J. Maddox,et al.  Fatigue strength of welded structures , 1991 .

[7]  Paolo Lazzarin,et al.  A NOTCH INTENSITY FACTOR APPROACH TO THE STRESS ANALYSIS OF WELDS , 1998 .

[8]  Timothy Russell Gurney,et al.  Fatigue of Welded Structures , 1980 .

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

[10]  E. C. Gomes,et al.  Fatigue performance of tungsten inert gas (TIG) and plasma welds in thin sections , 1999 .

[11]  F. V. Lawrence,et al.  Analytical and Graphical Aids for the Fatigue Design of Weldments , 1985 .

[12]  J. Solin.  Fatigue design : papers presented at the International Symposium on Fatigue Design organized and sponsored by VTT (Technical Research Centre of Finland) and held in Helsinki, Finland , 1993 .

[13]  T. Nykänen,et al.  A parametric fracture mechanics study of welded joints with toe cracks and lack of penetration , 2005 .

[14]  W. Brown,et al.  Plane strain crack toughness testing of high strength metallic materials. , 1966 .

[15]  Gary Marquis,et al.  A fatigue assessment method based on weld stress , 2006 .

[16]  Luca Susmel,et al.  Estimation of the fatigue strength of light alloy welds by an equivalent notch stress analysis , 2002 .

[17]  S. J. Maddox,et al.  An analysis of fatigue cracks in fillet welded joints , 1975 .