Robust Structural Design of an Active Aeroelastic Wing with Maneuver Load Inaccuracies

Abstract

A multidisciplinary design methodology for aircraft structures subject to inaccuracies in aerodynamic load predictions is presented. A statistical load-correction model is developed that is based on typical differences between loads as predicted by nonlinear and linear aerodynamic theories. Load corrections are propagated to a response function that represents the magnitude of structural redesign that would be necessary when the structure is subject to variation in the loads to which it was designed. The method is applied to an active aeroelastic wing concept, in which both the structural and control law designs are highly sensitive to variations in the aerodynamic loads. Computational fluid dynamics Euler analysis is used to construct the load-correction model. The most critical loading condition is then identified and used to redesign the structure and control-surface gear ratios. The redesigned structure was found to be 11% heavier and significantly more robust than the structure that was optimized with the linear loads only. The present methodology provides a way to account for load inaccuracies in the early phases of the design process, thereby, reducing the need for redesign late in the design process as load predictions become more accurate.