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Advanced Primary Composites Structures

Exploitable results

The APRICOS programme has focused on the technologies necessary for the development of composite fuselage structures with the aim to demonstrate a 30% life cycle cost saving over conventional metal aircraft. This target saving contained elements of initial purchase cost, mass saving (which might be translated into terms of range, payload and fuel costs) maintenance and operational costs. Different materials and process technologies were compared for the various component parts within a generic demonstrator panel. The results have permitted the identification of pre-design and processing technologies for advanced, affordable, composite fuselages. In parallel to technology development, key technical areas linked to the introduction of composite structures for fuselage applications have been clearly identified. Based on specifications developed in a previous BE programme, a certification approach has been proposed and design requirements identified. Stress methods for post buckling analysis and design criteria for skin stiffener failure were developed and validated against test results. Furthermore, impact behaviour of structures were extensively investigated and models successfully developed. Material specification for fuselage structures has been agreed and 10 materials evaluated. A philosophy of ranking was developed and materials compared using spidergraphics. Design concepts were presented for different applications and suitable technologies for the different elements have been identified. Innovative composite technologies were developed for the different elements: Liquid Resin Infusion and Resin Film Infusion for self stiffened skins and Resin Transfer Moulding for frames and doors. Using these technologies developed at subcomponent level, scale up has been demonstrated for the generic panel manufacturing. Assembly of such a structure was achieved under industrial conditions. Technology readiness has been gained during this project. From the cost analysis performed all along the project, it was concluded that a composite fuselage can be feasible. The very ambitious goal of a 30 % lower LCC than today¿s metallic fuselage structures has not been achieved in the completed analysis work, but the target cost has been approached. In some partner studies, the estimated LCC reduction has been in the 15% range, which is very encouraging indeed. The APRICOS project was the first step along the R&D path required to achieve products in service. By providing initial confidence for the cost issue and technological feasibility of a large composite fuselage, it contributed significantly to the longer term industrial targets set for the aeronautic technologies. It permitted to have a common understanding and an harmonized approach of the technical solutions for a composite fuselage. This has resulted in the development of common knowledge, for material and processes tested and a common certification philosophy. The large amount of benefits that came from this programme justified a follow up of the research to reach the next steps of the building block approach in terms of concept validation through a full scale barrel test and in terms of technology development through more integrated full scale structures, in order to achieve the goal of a composite fuselage in service.