Robust Aeroelastic Tailoring For Composite Aircraft Wings

An optimisation framework is presented for robust design configuration of composite aircraft wings through consideration of uncertainties in material properties, ply orientations and thickness. A detailed Finite Element wing box model of a regional jet airliner is used as a benchmark. The wing structure is optimised for minimum weight with strain, buckling, flutter/divergence and gust constraints. Polynomial Chaos Expansion approach is used to efficiently quantify the effects of uncertainty in the design parameters. This method is used to determine the probability of flutter/divergence occurring, and the allowable root bending moment being exceeded, for any given design specification which is then optimised using a Particle Swarm Optimisation algorithm. Results are compared with deterministic solution for optimal flutter speed and minimum root bending moment. Three layup strategies were undertaken, a first which only consists of 0⁰, ±45⁰ and 90⁰ plies, a second which included ±30⁰ and ±60⁰ plies and a third which also uses ±15⁰ and ±75⁰ plies. A minimum improvement in reliability of 32.6% is achieved for laminate with 0⁰, ±45⁰ and 90⁰ plies and highest reduction in mean root bending moment value is obtained with inclusion of ±30⁰ and ±60⁰ plies. The layup strategy with 0⁰, ±30⁰, ±45^0, ±60⁰ and 90⁰ plies give the optimal robust solution for both flutter and root bending moment responses.