Computational fracture mechanics assessment of adhesive joints

In automotive and aeroplane structures adhesive joining is recognized as a potential future technology for a variety of material systems where traditional fastening methods would be inappropriate. Well known examples include fiber reinforced composites and polymers. Additionally in certain circumstances, adhesive bonding of steel structures can provide benefits such as improved stiffness and/or reduction of stress concentrations common with welded, riveted, and bolted joints. Nevertheless, there is hesitation on the part of industry to replace traditional fasteners in primary structural applications, mainly due to the limited understanding of joint performance over the life of structures. This work focuses on computational assessment of crack in a metal-adhesive-metal joint, which could be typically encountered in an automotive structure. Based on extensive numerical analysis we are trying to give a general description of the crack tip fields and to clarify the known issue with the geometry-dependent fracture energy for failure of adhesive layer. Furthermore, we apply the cohesive zone model to examine feasibility of such models and to give a general prediction of the geometry-dependence of the adhesive joint failure. The numerical results are verified by the known experiments.