Numerical Study on the Compressive Behaviour of Repaired Composite Panels

Despite their attractive properties, composites are characterized by a high susceptibility to damage arising from impact loading. BVID may induce delaminations and further intra-laminar damages, due to intrinsic weakness of composite laminates in the out-of-plane direction, which can considerably reduce the stiffness and the strength of composite components. Impact damaged composite structures require component replacement or repair. Considering economic and environmental benefits, composite repair is preferred as the main and cost-effective approach able to fully restore the structural integrity of the damaged components. This work is aimed to numerically study the compressive behaviour of an impact damaged aeronautical composite stiffened panel undergoing repair. Two Finite Element based models have been developed in the ABAQUS FEM platform to numerically simulated the mechanical behaviour of the investigated composite structure: a model for the pristine configuration and a model for the repaired configuration. In the repaired configuration, a bonded stepped patch with an external ply for the skin's external surface has been placed. According to the repair scheme, the replacement of six parts of carbon-fiber plies in concentric circles by new plies with increased radius, allowing plies overlapping, has been considered. Linearized buckling analyses and static non-linear buckling analyses have been performed to study the panels' compressive behaviour and the effects of repair process on mechanical performances in terms of stiffness and deformed shapes evolution during compression, for the pristine and the repaired configuration.