Proposal of a modelling approach for the prediction of a crack initiation in a bonded assembly ; Proposition d'une démarche de modélisation pour la prévision de l'amorçage d'une fissure dans un assemblage collé sous des sollicitations statiques

In a context of aircraft weight reduction for a decrease of the fuel consumption, joining by bonding represents an interesting option to screwed assemblies. However, the advantages of bonded assemblies are not completely exploited especially because of the lack of confidence in the engineering design methods being used for them. That is why the purpose of this work was to propose a modelling approach for the prediction of a crack initiation in this kind of assemblies under static solicitations. Numerous parameters play a major role on the initiation in a bonded assembly. In particular, the initiation load depends highly on the adhesive thickness of the assembly. Therefore, on the other hand, the influence of this parameter has been estimated by a coupled criterion-based approach for which a new definition of the mode mixity has been proposed in order to express the dependency of the adhesive strength and toughness to the loading mode. The application of the coupled criterion enabled to confirm numerically the influence of the adhesive thickness on the initiation observed experimentally in a single lap joint test; namely the thinner the adhesive thickness, the greater initiation load. One the other hand, the knowledge gained has been built on by taking into account the adhesive thickness in a cohesive zone model composed of the same ingredients than the coupled criterion but which can be used in 3D structures. The cohesive zone model thus proposed shows the influence of the adhesive thickness on the initiation identified with the coupled criterion. Finally, the contributions and the limitations of the modelling approach proposed have been highlighted through comparisons with experimental results of literature. ; Dans un contexte de réduction de la masse des aéronefs pour une diminution de la consommation de carburant, l'assemblage par collage représente une alternative intéressante aux assemblages boulonnés. Toutefois, les avantages des assemblages collés ne sont pas pleinement exploités, notamment de par le ...