New welding technology for lightweight aircraft
Mechanical joining technologies are highly entrenched in the aviation industry, with a typical fuselage requiring approximately 50 000 rivets across its surface for joining integral structures. Laser welding is a critical enabling technology for reducing the weight of aircraft fuselage through increased use of aluminium and can replace riveting of aircraft structures. Within EXTRA-LASER (Extrapolation and technical and economic study of a laser beam welding technology (extra-laser)), researchers conducted a comparison between LBW and mechanical joining in terms of environmental impact, safety, process efficiency and manufacturing costs of aircraft structures. Work activities were based on the use of a representative structure of a Clean Sky technology demonstrator – a flat panel with four stringers. Given that most fatigue failures originate at fastener holes in riveting, laser welding enhances the overall safety of the structure. Laser-welded structures have improved damage tolerance due to better material properties and process flexibility. Proper process conditions help ensure that the metallic alloys have a good microstructure that strongly influences porosity formation, corrosion resistance and susceptibility to hot cracking. By exploiting innovative aluminium-lithium alloys for the demonstrator panel and without changing its structural design, the team obtained a structure that was 20 % lighter. Processing time of the laser-welded structure dropped by 50 % compared to its riveted counterpart. The new process seems to be more energy consuming during manufacturing than the riveting structure. However, lighter weight will mean decreased aircraft fuel consumption. Manufacturing costs are significantly higher for the LBW structures because of the high prices of aluminium and lithium. Project results can strengthen the use of laser welding as a clean manufacturing process with low harmful emissions. The increased use of LBW for integral structures also eliminates the need for riveting, which is very noisy and monotonous, thus helping create a more peaceful work environment.
Keywords
Lightweight, aircraft, laser beam welding, riveting, aluminium, EXTRA-LASER
