Multidisciplinary Optimization of Composite Wings Using Refined Structural and Aeroelastic Analysis Methodologies

Abstract

An integrated multidisciplinary procedure has been developed for structural and aeroelastic optimization of composite wings based on refined analysis technique. A refined higher-order theory is used to analyze composite box beam, which represents the load carrying member of the wing. Unsteady aerodynamic computations are performed using a panel code based on the Doublet Lattice Method. Flutter/divergence dynamic pressure is obtained by the Laplace domain method through rational function approximation of unsteady aerodynamic loads. The objective of the optimization procedure is to minimize wing structural weight with constraints on flutter/divergence speed and stresses at the root due to the static load. Composite ply orientations and laminate thicknesses are used as design variables. The Kreisselmeier-Steinhauser function approach is used to efficiently integrate the objective function and constraints into a single envelope function. The resulting unconstrained optimization problem is solved using the Davidon-Fletcher-Powell algorithm. Numerical results are presented showing significant improvements, after optimization, compared to a reference design.