Robust multidisciplinary analysis and optimization for conceptual design of flexible aircraft under dynamic aeroelastic constraints

Abstract

We present a computational framework for robust multidisciplinary design and optimization of flexible aircraft, suited for the conceptual design exploration phase. Constraints are representative of some dynamic aeroelastic effects, including flutter and gust-induced structural stresses. Uncertainties on wing structural parameters are considered, and reliability-based optimization under dynamic aeroelastic constraints is addressed by a Bayesian approach. This work details the implementation aspects, covering disciplinary software tools and the overall aircraft design suite, the optimization algorithm and the approach to propagate uncertainty efficiently. Results are thoroughly discussed for a reference aircraft, which is optimized in the study with respect to a few wing parameters including aspect ratio. The proposed approach is compared to a conventional design methodology assuming a rigid airframe. We show that when applied to slender and flexible wings, the latter can produce dangerous non-conservative results, as its predictions are too optimistic both with respect to efficiency and to aeroelastic safety.