Generalized stress intensity factors due to steady and transient thermal loads with applications to welded joints

This paper deals with the elastic and plastic stress fields induced by thermal loads in the vicinity of sharp V-notch tips in plates. Under the hypothesis of steady-state heat transfer and plane-strain conditions, the thermal and mechanical problem requires the numerical solution of an ordinary differential equation (ODE) system, obtained by extending the ‘stress function approach’. The intensity of the stress distributions ahead of V-notch tips can be expressed in terms of thermal notch stress intensity factors (thermal NSIFs), as for external loads. The problem becomes much more demanding in the presence of transient thermal loads. The residual asymptotic stress distribution arising from the solidification of a fusion zone during an arc welding process is obtained by considering different boundary conditions. An aluminium butt-welded joint is analysed after having modelled the weld toe region as a sharp V-notch. A finite element (FE) simulation of the welding process is carried out by means of SYSWELD code (version 2004.1) modelling the arc welding torch by means of Goldak's source. Near the weld toe, the intensity of the residual stress field is given in terms of elastic or elastic—plastic generalized NSIFs.

[1]  M. Beghini,et al.  Fatigue crack growth in residual stress fields : experimental results and modelling , 1994 .

[2]  D H B Mok,et al.  Finite Element Study of Residual Stresses in a plate T-Joint Fatigue Specimen , 1990 .

[3]  Ivo Babuška,et al.  The post‐processing approach in the finite element method—Part 2: The calculation of stress intensity factors , 1984 .

[4]  Bernard Gross,et al.  Plane elastostatic analysis of V-notched plates , 1972 .

[5]  P. Ponte Castañeda,et al.  Asymptotic Fields in Steady Crack Growth with Linear Strain-Hardening, , 1987 .

[6]  Vigilio Fontanari,et al.  Influence of post weld treatments on the fatigue behaviour of Al-alloy welded joints , 1998 .

[7]  J. Rice,et al.  Plane strain deformation near a crack tip in a power-law hardening material , 1967 .

[8]  Yuh J. Chao,et al.  Effects of temperature-dependent material properties on welding simulation , 2002 .

[9]  Huang Yuan,et al.  Analysis of elastoplastic sharp notches , 1994 .

[10]  Franco Bonollo,et al.  Investigation of electron-beam welding in wrought Inconel 706—experimental and numerical analysis , 2005 .

[11]  D. Radaj,et al.  Review of fatigue strength assessment of nonwelded and welded structures based on local parameters , 1996 .

[12]  G. Meneghetti,et al.  Fatigue strength of fillet welded structural steels: finite elements, strain gauges and reality , 2001 .

[13]  Paolo Lazzarin,et al.  From a local stress approach to fracture mechanics: a comprehensive evaluation of the fatigue strength of welded joints , 1999 .

[14]  J. Goldak,et al.  A new finite element model for welding heat sources , 1984 .

[15]  Barna A. Szabó,et al.  NUMERICAL ANALYSIS OF SINGULARITIES IN TWO DIMENSIONS. PART 2: COMPUTATION OF GENERALIZED FLUX/STRESS INTENSITY FACTORS , 1996 .

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

[17]  Antonio Blázquez,et al.  A simplified numerical analysis of residual stresses in aluminum welded plates , 1996 .

[18]  Z. Yosibash.  Thermal generalized stress intensity factors in 2-D domains , 1998 .

[19]  Franco Bonollo,et al.  The influence of phase transformations on residual stresses induced by the welding process—3D and 2D numerical models , 2006 .

[20]  Guy Pluvinage,et al.  The use of notch stress intensity factor as a fatigue crack initiation parameter , 1995 .

[21]  M. Williams,et al.  Stress Singularities Resulting From Various Boundary Conditions in Angular Corners of Plates in Extension , 1952 .

[22]  Shahram Sarkani,et al.  An efficient approach for computing residual stresses in welded joints , 2000 .

[23]  Dieter Radaj,et al.  Design and Analysis of Fatigue Resistant Welded Structures , 1990 .

[24]  L. Xia,et al.  Singular behaviour near the tip of a sharp V-notch in a power law hardening material , 1993, International Journal of Fracture.

[25]  Paolo Lazzarin,et al.  Plastic notch stress intensity factors for large V-shaped notches under mixed load conditions , 2001 .

[26]  T. Teng,et al.  Analysis of residual stresses and distortions in T-joint fillet welds , 2001 .

[27]  M. Mochizuki,et al.  Residual stress reduction and fatigue strength improvement by controlling welding pass sequences , 2000 .

[28]  Paolo Lazzarin,et al.  Notch stress intensity factors and fatigue strength of aluminium and steel welded joints , 2001 .

[29]  Yves Verreman,et al.  Early development of fatigue cracking at manual fillet welds , 1996 .

[30]  John W. Hutchinson,et al.  Singular behaviour at the end of a tensile crack in a hardening material , 1968 .

[31]  M. Stern.  The numerical calculation of thermally induced stress intensity factors , 1979 .

[32]  Zohar Yosibash,et al.  On solutions of two-dimensional linear elastostatic and heat-transfer problems in the vicinity of singular points , 1997 .

[33]  J. Beswick,et al.  Effect of Prior Cold Work on the Martensite Transformation in SAE 52100 , 1984 .