Extended finite element modelling of aluminium stepped-adhesive joints

Abstract

ABSTRACTFor the joint strength prediction of bonded joints, Fracture Mechanics-based techniques are often used. In this context, the tensile and shear toughness of the adhesives are two of the most important parameters to predict the joint behaviour. The Finite Element Method has been used for strength prediction in the last decades. Cohesive zone modelling coupled to a FEM analysis is generally accepted as an accurate method. More recently, the Extended Finite Element Method (XFEM) has emerged. This work aims to validate the XFEM to predict the behaviour of stepped-lap joints with different overlap lengths. Three adhesives, Araldite® AV138, Araldite® 2015 and Sikaforce® 7752, whose properties are quite different, were tested. Peel and shear stresses in the bondline were analysed, which allows an analysis of the behaviour of the three adhesives under different geometrical conditions. For the XFEM strength prediction, different damage initiation criteria were used, based either on stresses or strains. The damage law shape was also evaluated, namely the linear and exponential damage propagation laws. The XFEM was found to be adequate to predict the joint strength using the Quadratic Stress and Maximum Stress damage initiation criteria.