Analysis and numerical prediction of the delamination behavior of debonded asymmetric sandwich shells with a thin-walled skin considering plastic deformation

This paper analyzes the delamination behavior of asymmetric sandwich shells with one thin-walled aluminum skin. In-plane compression tests of specimens with a delamination of the aluminum skin show high dependencies of the failure loads and the debond behavior on the delamination size and its in-depth position relative to the adhesive layer. All delaminations proceed in an unstable manner within the foam core close to the adhesive interface. A FE model is created and correctly reproduces the specimen's deformation and buckling behavior. Its predictions of failure loads are conservative but show some deviations. Furthermore, the numerical simulations are used for the analysis of occurring plastic strains in the aluminum skin. As shown, they have major influence on the delamination behavior. Large portions of the debonded areas are plastically deformed and relatively large amounts of deformation energy are dissipated by the plastic deformation.