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Article Dans Une Revue Fatigue and Fracture of Engineering Materials and Structures Année : 2009

Fatigue crack initiation life estimation in a steel welded joint by the use of a two-scale damage model

Résumé

This work deals with the fatigue behaviour of S355NL steel welded joints classically used in naval structures. The approach suggested here, in order to estimate the fatigue crack initiation life, can be split into two stages. First, stabilized stress-strain cycles are obtained in all points of the welded joint by a finite element analysis, taking constant or variable amplitude loadings into account. This calculation takes account of: base metal elastic-plastic behaviour, variable yield stress based on hardness measurements in various zones of the weld, local geometry at the weld toe and residual stresses if any. Second, if a fast elastic shakedown occurs, a two-scale damage model based on Lemaitre et al.'s work is used as a post-processor in order to estimate the fatigue crack initiation life. Material parameters for this model were identified from two Wöhler curves established for base metal. As a validation, four-point bending fatigue tests were carried out on welded specimens supplied by `DCNS company'. Two load ratios were considered: 0.1 and 0.3. Residual stress measurements by X-ray diffraction completed this analysis. Comparisons between experimental and calculated fatigue lives are promising for the considered loadings. An exploitation of this method is planned for another welding process.

Dates et versions

hal-00449120 , version 1 (20-01-2010)

Identifiants

Citer

Nicolas Lautrou, David Thevenet, Jean-Yves Cognard. Fatigue crack initiation life estimation in a steel welded joint by the use of a two-scale damage model. Fatigue and Fracture of Engineering Materials and Structures, 2009, 32 (5), pp.403-417. ⟨10.1111/j.1460-2695.2009.01344.x⟩. ⟨hal-00449120⟩
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