Numerical analysis and optimisation of cylindrical adhesive joints under tensile loads

This study is concerned with increasing the performance of adhesively bonded structures. Adhesively bonded joints offer many advantages, but stress singularities can contribute to the initiation and the propagation of crack in adhesive joints. Therefore, designing adhesively bonded joints which strongly limit the influence of edge effects can significantly increases the transmitted load by the assembly. Cylindrical joints are associated with high substrate strength in the radial direction, meaning that peel and cleavage forces have different effects compared to simple lap joints. But, for such assemblies, edge effects also exist. The aim of this paper is first to analyse stress concentrations in cylindrical joints in the case of axial loadings, starting from refined finite element computations under a linear elastic assumption. Thus as the stress state in the adhesive thickness can be complex associated to edge effects, simplified methods can lead to an overestimation of the transmitted load by the assembly as they generally are not able to represent effects of stress concentrations in the adhesive thickness. Secondly, geometries which strongly limit the influence of edge effects are proposed. An optimisation of the maximum transmitted load of cylindrical joints is proposed using a pressure-dependent elastic limit of the adhesive.