Design and analysis of thermoplastic welded stiffened panels in post-buckling

The Clean Sky 2 “SmarT mUlti-fuNctioNal and INtegrated TP fuselaGe" STUNNING project focusses on the next generation composite fuselage with emphasis on manufacturing techniques such as thermoplastic welding. Welded multi-stringer panels are investigated in this paper, with emphasis on the buckling and skin-stringer separation behavior. The multi-stringer panels are designed to approximate the structural behavior of the lower half of the MultiFunctional Fuselage Demonstrator of the STUNNING project. In particular, a section of the fuselage is analyzed using Abaqus with a dynamic implicit analysis, and the results of this analysis are used for the design of the multi-stringer panels, taking manufacturing considerations also into account. The panels have three omega stringers and a length of 500 mm. The three stringer configuration allows to study the middle stringer in pristine and damaged configuration with minimal influence of the free edges and boundary conditions. It is seen that the multi-stringer test panels show very similar buckling and skin-stringer separation behavior compared to the fuselage section. The first panels have been manufactured by project partners NLR and GKN Aerospace Fokker and will be tested at the Faculty of Aerospace Engineering at Delft University of Technology.