Experimental and three-dimensional global-local finite element analysis of a composite component including degradation process at the interfaces

A specimen is studied in order to analyse the stringer runout effect in a specific design. An experimental test was carried out in several stages until specimen collapse, allowing the damaged regions and their characteristic geometric dimensions to be identified by ultrasound inspections. Several numerical analyses based on finite element method of the component were performed using the commercial software ABAQUS. These numerical analyses aimed to study in detail the onset and propagation of damage in the skin-stringer joint during the load procedure. Due to the high computational cost that this kind of procedure usually requires, a global–local approach was performed, comparing the two techniques offered by the software ABAQUS: Submodeling and Shell-to-Solid Coupling. Shell element typology was used in both cases for the global model. In order to estimate the extension of the critical zone in the specimen, the adhesive layer was modeled by means of solid elements. With reference to the local analysis, laminate continuum elements were selected to discretize the skin and the stringer, whereas the adhesive was represented by interface cohesive elements to take the damage evolution into account. A final correlation was carried out between numerical predictions and experimental results of the damaged regions in the component at several load levels.