GEORGE LAMPEAS; EVANGELOS CARELAS; PANAGIOTIS KORDAS ; ALEXANDRA KARANIKA; KONSTANTINOS FOTOPOULOS
DOI Number: 10.13009/EUCASS2023-014
The paper discusses a reliable, high versatility, cost efficient approach for petforming full-scale fuselage panel testing and validation of the respective novel stiffening design concepts, as well as the way to confidence enhancement in computational models towards safer and more light-weighted aircraft designs. A methodology to mature low-cost testing technologies for demonstration of the structural integrity of representative aircraft fuselage panels in representative static and fatigue loadings, for the next generation Aircrafts is presented. To mature up to Technology Readiness Level TRL6 the environmentally friendly manufacturing and surface treatment technologies developed in the metallic materials technological stream of Clean Sky 2 core project ecoTECH project [1 ], a high versatility, cost efficient approach for performing full-scale fuselage panel testing is required. The new manufacturing technologies include Friction Stir Welding for the replacement of riveting and mechanical milling for the replacement of chemical milling. The above-mentioned methods are combined with new surface treatments like the Chromium free anticorrosive surface treatments, developed and performed by Hellenic Aerospace Industry, Thin film Sulphuric Acid Anodizing and AC131 sol gel developed with a totally free Cr preparatory steps of cleaning and etching, and a totally Cr free post treatment step of Sealing after the anodizing. The basic anticorrosive surface treatments are combined with a new Chromium free primer, developed and industrialized by AKZO NOBEL with the commercial name: Aerolith CF Primer 2210, and water based top coat. The steps to scale-down the experimentation at the stiffened panel level and provide the opportunity to effectively validate state-of-the-art designs than previously attainable are presented in the present paper, as part of Clean Sky 2 project Demonstrate which is CfP of ecoTECH [2]. The proposed methodology comprises the development of a test bench and its application for the execution of static tests on advanced metallic curved integrally stiffened full-scale panels, representative of a business jet fuselage structure; and the execution of an endurance test on an integrally stiffened 4th generation Al-Li curved panel, under a realistic load spectrum representative of the aircraft mission profile. The design of the rig and the experimental process are supported by validated multi-scale simulation models, focusing on the predictions of static, buckling and post buckling deformations, as well as on the crack initiation and damage growth. The virtual testing methodology was used for the definition of the stiffened panels boundary and loading conditions, such that they are fully representative of the aircraft full-barrel fuselage in-flight loading conditions. It can be concluded from the performed research activities, that the development of the innovative, cost-efficient, and easily adaptable to a wide range of curved panel lengths and curvatures fuselage panel full-scale test bench concept, has been proven capable to introduce the desired representative boundary/ loading conditions and successfully validate the novel manufacturing and surface treatment processes.