In traditional 3D variation simulation (stack-up’s) it is common to consider that the parts are rigid. However, often in production forces are applied manually or by different fixturing solutions to assure that requirements on offset are fulfilled before welding parts together in an assembly. This causes the parts to bend and rigid analysis is therefore not valid. Depending on assembly sequences and geometry variation of incoming material, different fixturing forces need to be applied from component to component to assure the right fit in the seam before welding. It may even be necessary to use active fixturing where the forces are varying during the welding process. The welding process itself also contributes with variation that needs to be considered in order to fulfil geometrical requirements.
This project proposed a novel way to combine variation and welding simulation to support the design of future welding fixtures for aircraft engine components. Non-rigid Geometrical Variation Simulation were further developed to optimise locator and support positions in order to minimise geometrical variation in the weld gap and also take fixturing forces into consideration. Computational Welding Mechanics simulations with integrated control functions were further developed to prescribe fixturing forces for maintaining specific tolerances ahead of the weld for a stable weld process.
The simulation areas were combined and integrated to support the design of a physical welding fixture suitable for fabrication of aircraft engine components. The results were demonstrated virtually and physically.
Green and sustainable aero engines require weight reduction. For the open rotor technology, with rotating Ni-based superalloy components this is enabled by fabrication (welding) methods where a number of small parts, often in different materials, are welded together. In this type of fabricated structures, variation from manufacturing of the individual parts, from the fixturing and assembly process and from the welding process itself accumulates and propagates through the structure and creates geometrical variation in the final subsystem. This in turn has an influence on the ability to meet requirements on aerodynamics and life. It is therefore extremely important to have a reliable process to control how variation affects the final welded geometries. Therefore, the GeoVar project combined state of the art variation simulation with welding metallurgy, welding simulation and fixture design.
The main result in the project was a novel approach on how to combine variation simulation and welding simulation to optimize fixture design and tolerances to meet geometrical requirements. The method contributed to decreased development time and cost and increased product quality for welded areo-structure components.