A multi-disciplinary optimisation model for passenger aircraft wing structures with manufacturing and cost considerations
In traditional aircraft wing structural design, the emphasis has been on pursuing the minimum weight or improved performance. The manufacturing complexity or cost assessments are rarely considered because it is usually assumed that the minimum weight design is also the minimum cost design. However, experience from industry has shown that this is not necessarily the case. It has been realised that in the cases where no manufacturing constraints are imposed, the extra machining cost can erode the advantages of the reduced weight. As manufacturing cost includes material cost and machining cost, whilst reducing weight can reduce the material cost, if the manufacturing complexity increases greatly as a result the overall cost may not go down. Indeed, if the manufacturing complexity is not checked, the machining cost could increase by more than the amount by which the material cost reduces. To enable the structural manufacturing complexity to be controlled, manufacturing constraints are established in this thesis and integrated into the optimisation of the aircraft wing structural design. As far as the manufacturing complexity is concerned, attention has been paid to both 3-axis and 5-axis machining. The final designs of optimisations with manufacturing constraints prove the efficiency of these constraints in guiding the design in the manufacturing-feasible direction.