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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - MEPAFUS (Metitalia prototype tooling for fuselage panel)

Teaser

Summary

The MEPAFUS project is aimed to the development, design and fabrication of an innovative tool chain to allow the fabrication of a large composite fuselage panel for a regional Aircraft.
The innovative tool chain is able to allow fabrication other panel stiffened by several omega shaped stringer in one shoot i.e. cocuring fresh stringer with fresh skin. In this way the process is based on a unique autoclave curing with saving of energy in respect to alternative process like cobonding (some elements already cured joined to other elements uncured), secondary bonding (elements already cured joined by adhesive film) fastening.
In addition the tool chain allow the automatic lamination of skin on an auxiliary tool while the cure tool is in autoclave to perform the cocure of panel. When ready the skin is downloaded on cure tool to proceed to the cure of next panel. In this way the lamination tool and cure tool are specialized for their specific use. Moreover preparation of skin and stringer using auxiliary tool allow to reduce the overall flow time of panel production.
The development of tool chain has been based on partners experience in complex tooling and on Topic Manager indications. The tool chains has been developed considering the need of coordination between lamination and cure tool. In addition tool chain include several composite elements developed to reduce effects of differential thermal expansion and mass to be heated during panel cure in the autoclave. Finally the tool has been provided with all the necessary accessory (plug, caul plate, spacers) to allow the complex bagging scheme necessary to cocure stringer on the skin.
Geometry of parts with its complexity pose several challenges in obtaining the necessary dimensional tolerances. Moreover the air tightness necessary on lamination tool and cure tool was also challenging due to the big dimensions of tools.
In the development of tool chain whenever possible it has been considered the goal of energy saving selecting the lighter material compatible with functional requirements. In addition the possibility of recycle of material at end of life of tool chain has been also considered.

Work performed

Work start with several meeting with the Topic Manager to establish tool list and lay out of major tool. After formal approval from TM in a dedicated PDR (Preliminary Design Review), the detailed design, including stress analysis, of each tool has been performed and approved by TM at dedicated CDR (Critical Design Review).
Finally each tool was fabricated and inspected providing when necessary to their coordination in Metitalia tooling facility. Dimensional and functional inspection of tool was performed and documented to TM. Finally all the tools has been delivered to TM. After some rework at TM site the tools are now available to TM to fabricate the first fuselage panel.

Final results

The cocure of big stiffened panels for application on commercial aircraft is on the leading edge of technology to make affordable the use of composite materials. As a matter of fact cocure save autoclave cycle and reduce production flow time but pose several challenges. These includes coordination of wet parts, the smoothing of gap and step to avoid mark off and fiber distortion, execution of leak free vacuum bag.
The tool chain developed by partners, according to TM indications, has tried to solve trough proper design, material selection and proper coordination most of these problems and put the base to use the same concept for production tool to be used in novel commercial aircraft in development from European aerospace company holding the competitive advantages in respect to hold and new competitors like China and Russia.