DAHLIAS

Automated welding processes to assemble aircraft structures using standard high strength non-weldable aluminum alloys could allow strengthening of the global leadership and competitiveness of the European aeronautics industry against low-cost and manual manufacturing industries of emerging countries. In this project, such a joining technology – the refill friction stir spot welding process (Refill FSSW) – applied to standard high strength aluminum alloys, will be investigated to optimize the manufacturing of fairly complex aircraft structures such as fuselage sections. Friction-based processes could lead to benefits when compared to the traditional riveted structures. They produce welded joints without flaws or defects and superior mechanical properties. Furthermore, the heat input and residual stress are comparatively low. The adoption of this welding process provides weight and costs savings of about 15%. Moreover, assembly time and cost will also be reduced due to fewer assembly operations.
The DAHLIAS project aims at closing the knowledge gaps regarding the systematic development of a new production technology (Refill FSSW) coupled with a new adhesive sealant (hybrid joining) and the respective questions when applying this technology in industrially produced aircraft structures, such as quality control, process monitoring and damage tolerance behavior. These aims fulfil and compliment the challenges identified in the call (Optimization of hybrid joining (Refill FSSW and adhesive bond) for increasing mechanical properties and corrosion protection of the joints) with additional topics leading to the industrialization of this technology, i.e. elevation of the present TRL (currently app. TRL5 to TRL6).

Participants: Helmholtz Zentrum Hereon (Coordinator), Institut de Soudure, Belgisch Instituut voor Lastechniek VZW, Chemetall GmbH, Tra-C Industrie SAS