Abstract

Considering the latest introduction of the dry multiaxial fabrics into Aeronautical applications/programs (wing skins, Vertical Tail Plane [VTP] skins, winglets, bulkheads, cargo doors, etc.), together with the lack of automation for the preform creation and its deposition onto the corresponding molds, this paper will cover different potential solutions for the manufacturing of skins and stiffeners. In all cases, looking to the automated dry multiaxial fabric preform creation, lay-up and forming.

Abstract

In recent years many of the developments in the field of composite materials have focused on processes of dry carbon fiber, and efforts have been directed to achieve with these materials the same levels of industrialization as with pre-impregnated materials, since it is a technology of low cost and with a high productivity.

The objective of this project has been to develop dry carbon fiber manufacturing methods to obtain an automated, robust and efficient process for reaching manufacture the lower skin of a wing with stringers and integrated spars by automatic laying in Fiber Placement, posterior Hot forming and finally a process of resin infusion by "Vacuum Assisted Process".

To achieve this objective, the Fiber Placement machine has been set up to optimize the laying parameters for the processing of the material to be used (½” Hexcel Hi-Tape fiber).
On the other hand, several tests of hot forming of this laminates have been carried out by means of the previous process, modifying process variables, tooling details and forming bag configuration, in order to obtain the preforms of stringers and spars.

Finally, the integration of spars, stringers and skin was performed by a resin infusion process using the VAP technique "Vacuum Assisted Process".

Abstract

The aim of this project had been the infusion specimens manufacturing to support design, analysis and qualification for the “Outcome Lower Skin” pyramid structural tests inside the Clean Sky 2 programm. It is the reinforcement lower skin structural tests pyramid for the C295 military aircraft from Airbus Defence & Space.

Along the project UD dry fiber manufacturing process had been developed until to obtain an automatic, robust and efficiency process in order to be able to manufacture a lower skin with stringers and spars integrated and that will be able to compete with the typical prepreg process with regard to fabricability, ratio, performance and cost.

The manufacturing process includes the dry fiber pre-forms automatic lay-up by AFP (Automated Fiber Placement), a hot-forming process for the stringers and finally a process infusion by VAP (Vacuum Assisted Process). To achive this goal, the AFP has been set up to optimize the laying parameters for the processing of the material to be used (½” Hexcel Hi-Tape fiber) and RTM6 resin. On the other hand, several tests of hot forming had been carried out modifying process variables, and several infusion bags configurations had been used to stringers and skin integration by infusion (VAP) until to find the key process parameters to obtain valid parts for the structural test pyramid.

Abstract

The current work has been performed in the context of FUSINBUL, an European project framed within CleanSky2 research programme funded by the EU’s Horizon 2020 (Grant Agreement nº 831946). The scope of this project is to accomplish the full barrel demonstrator tests, needed to certify the new conception of fuselage created and manufactured in the Green Regional Aircraft context. Two advanced manufacturing processes for composites materials (prepreg cobonding process in autoclave and LRI infusion process out of autoclave) are developed and validated to achieve full scale innovative pressure bulkheads for Regional Aircraft Fuselage barrel on-ground demonstrators. The design of the tooling has taken into account the main needs of both manufacturing processes to carry out the bulkheads and the industrial requests. In addition to this, innovative tool technologies have been developed and applied, such as cast aluminium by lost foam casting, precise but robust indexing system split and seal system of tool too large to be fabricated one shot, then precisely assembled with no gap or step. For both manufacturing processes, the most advanced techniques of lay-up are used to reduce labor costs and increase the level of industrialization in serial production to achieve bulkheads with a diameter of 3.5m and the required standards in aeronautical industry.