Design of UAV-S4 composite morphing wing

The main purpose of this work is the application of morphing wing technique to the UAV-S4 wing using actuators placed inside the wing box. Displacements were applied over the flexible skin upper surface made of laminate... [ view full abstract ]

The main purpose of this work is the application of morphing wing technique to the UAV-S4 wing using actuators placed inside the wing box. Displacements were applied over the flexible skin upper surface made of laminate composite, to change wing airfoil shape. These displacements will correspond during experimental wind tunnel tests to the ones given by actuators placed on the flexible skin. The airfoil will change its shape due to the drag force with the aim to reduce the operational fuel consumption, and therefore the atmosphere pollution.
The composite optimization methodology used for the design of the upper surface structure is done in three phases. During the first phase, the free-size optimization that is one type of topology optimization for composite laminates, allowed us to generate design concepts (material distribution in the structure by creation of ply-bundles where each bundle contains plies of different orientations); constraints based on displacement responses and buckling modes, and manufacturing constraints are used. During the second phase, ply-Bundle sizing optimization was performed to control the thickness of each ply and to define the optimal number of plies for each bundle while considering all constraints defined in the first phase. During the third phase, the ply-staking sequence optimization was applied to determine the detailed stacking sequence by considering all behavioral and manufacturing constraints above defined. This optimization was performed to reach all airfoil shapes considered as optimal in of drag force reduction.
Finite Element structural model of the wing has been developed using Hypermesh, a module of Altair HyperWorks Software. Optimization was performed using OptiStruct 12.0. After the optimization process, an optimal structure of the changeable wing was found. Airfoil shape analysis was performed to observe if the structure allowed achieving the defined optimal shapes, then the actuating forces were calculated for every actuator to make possible the choice of actuators to be used in the wing box in order to achieve the expected optimal airfoil shapes. This study needed to be followed by manufacturing and testing of this new model in order to validate its new morphing design.

Keywords: Morphing wing, composite laminate, ply-bundle, free-sizing optimization, ply-sizing optimization, ply-staking optimization, actuating force.