Multiobjective topology optimization for a multi-layered morphing flap considering multiple flight conditions

Abstract

A morphing wing can deform its geometrical shape seamlessly and continuously to improve aerodynamic performance. In our previous study, a multi-layered compliant mechanism composed of stacked compliant mechanisms was proposed as the internal structure of the morphing flap to improve the design flexibility of the deformation shape. Each layer has an independent structural configuration that can be supported under an independently applied load. By connecting layers throughout the wing skin, the multi-layered compliant mechanism is worked as a single morphing flap. This study expands the design flexibility of the multi-layered compliant flap to achieve different morphing shapes by considering multiple flight conditions. For this purpose, load cases with different actuation forces according to the flight conditions are introduced and the design problem is formulated using a multiobjective optimization problem. Through numerical examples, several Pareto configurations of the multi-layered flap are demonstrated to facilitate deformation to yield different desired morphing shapes to maximize the lift-to-drag ratio or maximum lift coefficient. In addition, the trade-off between the two objective shapes is examined to investigate the effects on the values of these functions and the resulting configurations.