Micromechanical Analysis of Constraint Effect on Fracture Initiation in Strength Mismatched Welded Joints


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In this paper the micromechanical approach to ductile fracture was applied in a study of constraint effect on crack growth initiation in mismatched welded joints. The single-edged notched bend specimens (precrack length a0/W=0.32) were experimentally and numerically analyzed. The coupled micromechanical model proposed by Gurson, Tvergaard and Needleman was used. Constraint effect was tested by varying widths of the welded joints (6, 12 and 18mm). Highstrength low-alloyed (HSLA) steel was used as the base metal in a quenched and tempered condition. The flux-cored arc-welding process in shielding gas was used. Two different fillers were selected to obtain over- and undermatched weld metal. The micromechanical parameters used in prediction of the crack growth initiation on precracked specimen were calibrated on a round smooth specimen. The difference in fracture behavior between over- and undermatched welded joints obtained in experimental results was followed by numerical computations of void volume fraction in front of the crack tip.



Edited by:

Dragan P. Uskoković, Slobodan K. Milonjić and Dejan I. Raković




M. Dobrojević et al., "Micromechanical Analysis of Constraint Effect on Fracture Initiation in Strength Mismatched Welded Joints", Materials Science Forum, Vol. 555, pp. 571-576, 2007

Online since:

September 2007




[1] K-H. Schwalbe: Basic Engineering Methods of Fracture Mechanics and Fatigue (GKSSForschungszentrum, Geesthacht 2001).

[2] M.C. Burstow and I.C. Howard: J. Mech. Phys. Solids Vol. 46 (1998), p.845.

[3] N. Gubeljak, I. Scheider, M. Kocak, M. Oblak and J. Predan: 14 th European Conf. on Fracture, Cracow, Poland (2002), p.647.

[4] I. Peneulas, C. Betegon and J.J. del Coz: 9 th European Mech. of Mater. Conf. - Local App. to Fracture, Moret-sur-Loing, France (2006), p.285.

[5] A.L. Gurson: J. Engng. Materials and Technology Vol. 99 (1977), p.2.

[6] V. Tvergaard: Int. J. Fracture Vol. 17 (1981), p.389.

[7] V. Tvergaard and A. Needleman: Acta Metall. Vol. 32 (1984), p.157.

[8] P.F. Thomason: Ductile Fracture of Metals (Pergamon Press, Oxford 1990).

[9] J. Besson et al: Local Approach to Fracture (Les Presses de l'Ecole des Mines, Paris 2004).

[10] Z.L. Zhang, C. Thalow and J. Odegard: Eng. Fract. Mechanics Vol. 67 (2000), p.155.

[11] G. Bernauer and W. Brocks: Numerical Round Robin on Micro-Mechanical Models - Results (ESIS TC8 - GKSS Research Center, Geesthacht 2000).

[12] M. Rakin, Z. Cvijovic, V. Grabulov, S. Putic and A. Sedmak: Eng. Fract. Mechanics Vol. 71 (2004), p.813.

DOI: https://doi.org/10.1016/s0013-7944(03)00013-4

[13] M. Rakin, Z. Cvijovic, V. Grabulov, N. Gubeljak and A. Sedmak: Mater. Sci. Forum Vol. 453-454 (2004), p.175.

DOI: https://doi.org/10.4028/www.scientific.net/msf.453-454.175

[14] M. Dobrojevic: Crack Growth Modeling in Welded Joints (University of Belgrade - Faculty of Mech. Eng; Ph.D. Thesis - in Serbian, Belgrade 2006).