Overview
Friction stir welding (FSW) is now considered mature for simple applications and it has been shown that weight savings of up to 15% and cost savings of 20% can be achieved by its application. As a result FSW will be used in future Airbus aircraft such as A350. All major European airframe manufacturers believe that there are many more applications for FSW in the fabrication of cost effective integral metallic structure.
Examples include circumferential joints, tailored blanks, window frames, stringer to skin attachment, spars, enclosed sections and fittings.
Major technical advances need to be made beyond the current state of the art for FSW and integral metallic structure to achieve this. It is also necessary for FSW to be able to be applied to new geometries.
Therefore the objective for the proposed COINS project was to extend the application of integral metallic structure utilising friction stir welding by:
- advancing the state of the art of FSW technology,
- developing new geometries for FSW, and
- through innovations in design.
A group of fifteen partners including end users, research organisations, universities and a material supplier were brought together to achieve the Project objective. The project ran for 42 months.
The following activities were implemented during the project:
WP1. Updating process and test standards.
WP2. Production of integrated design solutions for structure containing FSW, including effects of other manufacturing processes, residual stresses and cracks.
WP3. Development of new applications for FSW including new alloys, the use of extrusions/forgings and techniques for applying FSW to new geometries.
WP4. Development of in production and in-service repair procedures plus the development of FSW as a repair tool.
WP5. Integration of FSW into the whole manufacturing cycle by combining with prefabricated parts and forming techniques, including creep-age forming.
WP6. Development of the primary FSW process innovations needed to realise the new applications. To deliver this programme a partnership consisting of 8 end-users, a material supplier, an equipment provider, 3 research organisations and 2 Universities has been assembled.
During the lifetime of the project, there were 12 consortium meetings for technical reviews. In addition, the first and second annual reviews with the EC project officer were held in conjunction with the scheduled technical reviews. There were as well numerous additional collaborative meetings since the start of the project. At the technical meetings progress were reported both by partner and by work package leader.
Funding
Results
This project demonstrated a good level of partner cooperation and collaboration between individual industrial partners and between industrial and academic partners. The overall technical progress in the programme was good and part of the final technical reporting was the compilation of a data design handbook cataloguing the project test results. It was agreed by the consortium that this would be a useful reference document for partners after the end of the project.
At the conclusion of the COINS project, most partners concluded that the original opportunities identified for exploitation remain in place. Dassault also identified an opportunity to manufacture structural parts on the Falcon 7x business jet. In general, the work performed within the project has heightened the level of technical readiness for both the friction stir welding process itself and its introduction as a means of unitising structural designs. More work will be required for most applications to be realised but the degree of risk has been minimised. For the OEM's or end-users the biggest challenge to the introduction of FSW is the on-going challenge that carbon fibre composites present to the use of metallic designs on future primary structures. Although metallic structures remain more than competitive on weight and indeed cost, the reality is that technology decisions on new aircraft are not always driven solely by engineering. Current in-house equipment resources, out sourcing to low cost suppliers, marketing strategies and political influences can have a major bearing on the final result. However, where a metallic solution is proposed it can be anticipated that FSW is likely to play a major role in reducing costs.
The dissemination activities within COINS have been numerous and varied, including 17 external papers and / or presentations as well as a dedicated workshop, held by GKSS, in Hamburg at the end of the project. Dissemination of the results will continue beyond the end of the project, with several partners contributing to a special issue of the Journal of Aerospace Engineering, which is part G of the proceedings of the Institute of Mechanical Engineers. The journal's editorial board approved this proposed special publication in March 2009 and appointed X. Zhang and S. Williams as the guest editors of this special issue. Publication is planned in late 2011 or early 2012 and is devoted to the research topics investigated in the COINS project.