In today's aerospace industry, nickel-based superalloy structures as introduced for the open rotor engine require additional specifications on built-in stress introduced during assembly. Aero engine parts and assemblies need to be considered as flexible because of their large size and small thickness. Considering also the influence of loads at the interface between components on the quality of assemblies, researchers developed tools to assess their actual behaviour. The aim of the EU-funded GEOVAR (Non-rigid geometry variation for fabricated aero structure) project was to reduce the number of testing loops. To this end, researchers proposed a new way to combine state-of-the-art geometric variations and welding mechanics simulations. The main result of GEOVAR was a 3D simulation methodology to obtain quantitative information about fixturing forces that need to be applied to ensure the right fit in the seam before welding. Merits of the GEOVAR approach were demonstrated with the assembly of smaller and bigger engine components consisting of several rigid and flexible parts. Researchers used simulation results to define the optimal working procedure and verified this against the results of tests carried out in the laboratory. The ability to accurately predict the effects of geometric variations, fixture forces and welding on aerodynamic performance and lifetime of aero engine components will be crucial in the manufacturing of next-generation aircraft. Better management of uncertainties promise robust assembly and higher production rate.
Geometric variations, welding, open rotor engine, aero engine, GEOVAR