INFLUENCE OF RESIDUAL THERMAL-STRESSES ON THE FRACTURE-BEHAVIOR OF HYBRID BONDED JOINTS

The objective of this work is to study the influence of the residual thermal stresses on the fracture behavior of hybrid composite-aluminium bonded joints. A modified DCLS specimen is designed and the strain energy release rate is determined using both an analytical fracture mechanics based method and a finite element method. The residual thermal stresses, which appear in the adhesive because of the difference between the curing and the service temperatures, are evaluated with a two-ply laminate specimen. Some rupture tests are performed on the DCLS specimens at different temperatures and for different geometries and materials. The results show a good agreement between analytical calculations, numerical analysis and experiments. The residual thermal stresses are never negligible in the considered hybrid bonded joints and do influence their fracture behaviors. Although the designed specimen is not adapted to study fatigue crack propagation, it provides a simple way to study the crack initiation and thus to characterize the rupture properties of the joint.