NEW METHODOLOGIES IN RELIABILITY-BASED DESIGN OPTIMIZATION FOR AEROSPACE STRUCTURES

The purpose of this paper is the design of a high aspect ratio wing, in which the main issue is to address the necessity of minimizing the wing mass and of avoiding aeroelastic problems, while maintaining a prearranged level of reliability. The impossibility to give a deterministic and exact solution to the problem is due to the intrinsic level of randomness both in the material properties and in the external loads. In particular, uncertainties in the aerodynamic forces are mainly caused by random gusts, which are accounted for by the present analysis following a model of the wing dynamics proposed by Cesnik and Brown. The wing design is then performed via a Reliability-Based Design Optimization employing a Non Dominated Sorting Genetic Algorithm. The objectives of the current analysis concern the structural weight as well as the location of the elastic axis, whose variation is determined over a pre-established set of control points in the spanwise direction. Lightness and aeroelastic stability are then achieved while satisfying the probabilistic constraints (e.g., on the maximum allowable torsion angle). The proposed analysis is still a work in progress, and only the results relative to the optimization of a single wing section are presented.