Development, structural analysis and numerical simulation of stiffened panels testing concepts under multi-axial loading

• Κύριος συγγραφέας: Πολυζωίδης - Σράιμπερ, Ιάσων
• Άλλοι συγγραφείς: Polyzoidis - Schreiber, Jason
• Γλώσσα: English
• Έκδοση: 2023
• Θέματα: Stiffened panel; Testing rig; Full-scale fuselage simulations; Cabin internal pressure load simulation; Facility optimization; Ενισχυμένα πάνελ; Διάταξη δοκιμών; Προσομοιώσεις ατράκτου πλήρους κλίμακας; Προσομοίωση φορτίων εσωτερικής πίεσης καμπίνας; Βελτιστοποίηση διατάξεων

The main objective of the current thesis is the establishment of the most ideal and cost-efficient testing rig configuration for the experimental investigation of the curved stiffened panel behaviour. The investigated panels should be capable to carry static loads, which are calculated from real flight conditions. A stiffened curved panel is constructed in the FE codes of ANSYS APDL and LS DYNA to enable comparisons between the numerical results of the full fuselage model and the stiffened panel model. The geometrical dimension and material properties of the Finite Element model (F.E.) are obtained by a typical passenger jet airplane. Aircraft fuselage structures consists of complex structures with components geometries which depend on numerous factors, such as aircraft size, mass, position of the component in the aircraft, flight conditions, etc. The complex fuselage section is simplified to a curved stiffened panel aiming to simulate its behavior with that of the fuselage. An extensive literature research will be carried out with the aim of reporting the experimental arrangements for stiffened panels and the advantages of the arrangement chosen. Initially, a full barrel fuselage section will be modeled to find the desired stress and radial displacement response to achieve at the panel level. From previous studies, three main testing rig models were considered most efficient and accurate, which carried internal pressure, tension and bending stresses. In the current thesis, emphasis will be placed on the simulation of internal pressure. For each one, the panel was modelled in F.E. format with the respected boundary and loading conditions. This step is essential for having realistic and representative full-scale fuselage simulations. The post processing data where then compared to the theoretical full barrel section model (fuselage response) and the data of each test-rig version will be collected, with the aim of choosing the best layout. The last part of this work is the introduction of an airbag in the experimental set-up to simulate the internal pressure of the cabin more realistically in normal flight conditions. Polyurethane foam pieces will be inserted between the panel stiffeners so that the loads are transferred evenly to the panel and the airbag is protected by them. At this point, the model will be optimized by changing the geometrical characteristics of the airbag, the rigid body and the foam components, aiming at the best possible distribution of pressure on the stiffened panel. Finally, a more detailed optimization will be made for the Rod arrangement and its geometrical characteristics in such way that the deviation of Radial Displacements and Stresses between panel and full barrel section level were minimized.