No abstract

This article describes an approach to predict the behaviour of an epoxy adhesive in bulk form in a marine environment. First, the material, the experimental conditions and the predictive framework are described. Then the experimental results are presented, which indicate that the effects on yield stress of either a uniform water profile or elevated testing temperature can be shown to be equivalent when plotted versus T-Tg. Moreover, a discussion of these results shows how they can be used to predict changes in the mechanical properties of the adhesive. Prediction results for yield stress are in good agreement when they are compared with experimental results for the case of a water profile gradient, in order to evaluate the relevance and limitations of the model.

WOSInternational audienceThis 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

No abstract

No abstract