Kim, Taeseong1; Kim, Jaehoon5; Shin, Sang Joon5; Kom, Do-Hyung6
1 Department of Wind Energy, Technical University of Denmark2 Aeroelastic Design, Department of Wind Energy, Technical University of Denmark3 Seoul National University4 Korea Aerospace Research Institute5 Seoul National University6 Korea Aerospace Research Institute
In order to enhance the aeroelastic stability of a tiltrotor aircraft, a structural optimization framework is developed by applying a multi-level optimization approach. Each optimization level is designed to achieve a different purpose; therefore, relevant optimization schemes are selected for each level. Enhancement of the aeroelastic stability is selected as an objective in the upper-level optimization. This is achieved by seeking the optimal structural properties of a composite wing, including its mass, vertical, chordwise, and torsional stiffness. In the upper-level optimization, the response surface method (RSM), is selected. On the other hand, lower-level optimization seeks to determine the local detailed cross-sectional parameters, such as the ply orientation angles and ply thickness, which are relevant to the wing structural properties obtained at the upper-level. To avoid manufacturing difficulties, only a few discrete ply orientation angles and an integral number of plies are considered as constraints. A genetic algorithm is selected as the optimizer at the lower-level. Use of the upper-level optimization causes a 13-18% increase in the flutter speed when compared to the baseline configuration. In the lower-level optimization, the optimization results were obtained considering the resulting failure margin and the location of the shear center.