TWI Ltd is leading a new project to improve efficiency and lower costs for aircraft manufacturing. The OASIS project will demonstrate the ability to manufacture aluminium aircraft structures using the latest developments in friction stir welding (FSW) and laser beam welding (LBW).
TWI-led OASIS project to reduce aerospace costs and improve aircraft efficiency
As part of the EU’s Clean Sky2 research programme, OASIS is funded by the Horizon 2020 programme and involves six European partners alongside TWI; ESAB (welding equipment supplier), VZLU (testing laboratory), Geonx (process modelling and simulation provider), Romaero (aerospace Tier 1 supplier), University West (materials science and metallography RTD partner), The Queen’s University Belfast (Virtual manufacturing and cost modelling). Clean Sky2 aims to develop innovative, cutting-edge technology to reduce CO2, gas emissions and noise levels produced by aircraft, while also strengthening European aero-industry collaboration, global leadership and competitiveness.
Traditionally, riveting has been the primary method for joining aluminium structures in aircraft fuselage manufacture, with large commercial aircraft fuselages containing hundreds of thousands of rivets. However, this joining method is time-consuming, expensive and adds weight, while placing holes and point loads in a cyclically pressurised structure, which can lead to long-term fatigue loading and corrosion. Further to this, riveting requires the time-consuming deburring of the holes prior to installing the rivets and redressing once they have been put in position.
The OASIS project will advance FSW, LBW and friction stir spot welding (FSSW) for the manufacture of complex lightweight aluminium structures, leading to the fabrication of two full-scale cargo door demonstrators for validation. Meanwhile, the inspection of the joints will be carried out in accordance with relevant aerospace standards.
The lack of riveting is expected to reduce weight by 10%, reduce joining time by 40%, save the use of consumables such as sealants, and lower the number of protective organic layers required to protect against corrosion. In addition, the project will undertake simulation and modelling of the effect of welding on structural integrity (structural and fatigue analysis of welded joints), study residual stress and distortion of the full structure, and take the input data from coupon level welding.
The lighter weight and improved aerodynamics of the rivetless construction will lead to increased fuel efficiency to improve the general cost-effectiveness of aircraft operation, help the environment by reducing CO2 emissions and save 30% on material usage compared with mechanical fastening / CNC machining.
In contrast to riveting, FSW, FSSW and LBW bring a lighter-weight distributed load path with the potential for improved structural stiffness and strength. With no holes and a smoother, aerodynamic surface, these methods create a more efficient and cheaper technique that should reduce the requirement for inspection and maintenance.
The developments made within this project will be transferable to the structural assembly of other aircraft parts and other industrial applications to allow for further advances and job opportunities.
Once implemented, the OASIS developments are expected to lower the cost of travel, reduce the lead times for product development, cut hazardous emissions and contribute to the need for a more efficient and environmentally-friendly means of air transport.
TWI is a world leading research and technology organisation with a focus on materials, engineering and manufacturing.