Aeroelastic tailoring of tow-steered composite wing boxes

Multi-disciplinary optimisation, including aeroelastic tailoring, and the intelligent use of advanced materials and manufacturing methods could provide a step change in aircraft efficiency for the future. In this context, the use of tow-steered composites is explored for tailoring the aeroelastic behaviour of a simple wing model. Using a genetic algorithm, first the wing flutter/divergence airspeeds are maximised and then the wing loads due to discrete gusts are minimised. It was found that the use of tow-steered laminates is beneficial compared to the use of straight-fibre laminates both in terms of increasing the flutter/divergence airspeeds (up to 13%) and in terms of reducing the wing root loads due to gusts (up to 24%). Whilst higher order fibre angle variations provide the best results, a linear fibre angle variation can already significantly reduce the correlated wing root loads due to gusts (up to 21%), and to a lesser extent increase the flutter/divergence airspeeds (up to 4%). Tow-steered laminates achieved improved aeroelastic behaviours compared to straight-fibre laminates by allowing the stiffness distributions and the spanwise bend-twist coupling to be optimised.