COMPASS: Functional laminates development. Components compatibility and feasibility assessment. Industrialization (Grant Agreement number 270616, Consortium composed of FIDAMC as coordinator and INTA) and HYBRIA: Hybrid laminates. Industrialization for aircraft nose fuselage (Grant Agreement number 306681 ) . Both projects have been partially funded by the European Commission, within the Seventh Framework Programme (7FP) through the Green Regional Aircraft belonging to Clean Sky.
In the pursuit of weight reduction, future structures will have to be multifunctional in the sense that a single component fulfils various objectives and was not necessary to develop independent structures for each of the functions required by the aircraft (acoustic and vibration attenuation, mechanical properties, electrical conductivity, etc.). Therefore multifunctional materials need to be developed and compared with current structural solutions to quantify the improvement offered by these new hybrid configurations over traditional composite architectures.
The use of layered composites in aircraft fuselage structural components offers the opportunity to embed interleaved layers of different materials in the skin laminates so that additional performances may be added while maintaining the structural efficiency. The presence of layers of damping materials inside the composite laminate normally results in an important reduction of mechanical properties. The goal of these two projects COMPASS and HYBRIA is to design composite laminates with integrated acoustic insulation without compromising the mechanical performance of the composite structure. In this frame, multifunctional CFRP laminates with insertion of vibro-acoustic damping materials have been investigated in both projects. Mechanical properties of the proposed solutions have been also evaluated to ensure that they are similar (and do not suffer a considerable reduction) with respect to the properties of the baseline configuration of the laminate before the multifunctional elements are added to it. Moreover, other characteristics like erosion, lightning protection (and electrical conductivity) and moisture ingress have been assessed to check the laminate behaviour compared with traditional composite laminates. Once an optimum set of possible multifunctional laminate concepts has been developed and its properties tested, the research ensured that the performance is kept when the size of the part is scaled up to full scale for the future industrial application.
After the materials screening/selection and architectures/mechanical studies carried out within the COMPASS project, hybrid structures were produced by means of industrial manufacturing processes within HYBRIA project. Three curved stiffened panels representative of the GRA cockpit fuselage were produced: hybrid skin fuselage with co-cured stringers of different shape section. Several manufacturing trials were carried out during the production of the demonstrators with the intention to validate innovative manufacturing concepts that will be implemented in the whole GRA cockpit production. NDT (non destructive testing) as well as dimensional analysis of the demonstrators were performed in order to assess the quality of the specimens produced.