Identify/Utilize Process Capability Information to Predict Variation in Aircraft Early Design 2007-01-3907

Process capability information, combined with simplified component geometric models and assembly variation transfer functions built from Monte Carlo simulations, can give aircraft designers early estimations of product variability. Such predictions traditionally must wait for detailed component designs-after many important sourcing and production decisions have been made and when alternative designs are no longer an option. An additional benefit of early variation analysis is identification of major contributors to critical assembly variation. This information can alert downstream part designers of potential problem areas and also identify key manufacturing processes capabilities that must be verified, measured, and/or improved.

This paper presents an efficient, top-down approach to move assembly variation analysis into early stages of aircraft development. Variation analysis starts with airplane level requirements (e.g. load capabilities, orientation of horizontal/vertical stabilizers) from which assembly requirements are derived in the form of geometric dimensioning and tolerancing callouts quantifiable in Quality Control. Next the contributors to a particular assembly requirement are identified. Finally, the major contributors are further characterized through a sensitivity study of metamodels or 3D variation analysis models. Once derived, variation models facilitate design tradeoff studies. Geometric parameters and processes capability assumptions are model input parameters and can be easily changed without rerunning simulation models. Good process capability information is required for an accurate variation analysis and production cost tradeoffs. A case study of a vertical fin has been used to demonstrate an application of the proposed approach.