Development of an SMA-based camber morphing UAV tail core design

Abstract

This paper presents a new design for the core of a lightweight tail section of an unmanned aerial vehicle (UAV) with camber-morphing horizontal and vertical stabilizers. The core of each stabilizer is composed of an aluminum spar, two active end ribs, and multiple inactive ribs. Each active end rib is composed of a solid leading compartment connected to a flexible corrugated trailing segment. Thermally activated shape memory alloy (SMA) wire actuators along the length of the corrugated segment are used to control the camber of each active rib. The SMA wires are extended through the hollow spar to increase the amount of actuation and are guided using polycarbonate pulleys. A parametric CAD model was created to automatically regenerate the corrugated trailing segment geometry based on trough height, width and angle, as well as the used NACA airfoil. The locations of the vertical webs are adjusted with each parameter set so that the webs are always at the trough centers for consistency. COMSOL's LiveLink was used to pass the generated CAD geometry to COMSOL, where finite element structural analysis is performed to study the effect of the geometric parameters on the camber deformation under SMA wire actuation and applied loads. The deformed shape of the trailing segment is then approximated as a third-degree polynomial and used to modify the four-digit NACA airfoil equation, generating a deformed shape for the airfoil. 2D computational fluid dynamics simulations are then performed to compute the lift-to-drag ratio for each structural configuration, from which the geometric parameters that maximize the performance of the stabilizer at the design speed can be selected. The proposed UAV SMA-based camber-morphing rear control section has been successfully manufactured and tested. Camber morphing up to 10.7°was successfully achieved and showed very good agreement with the numerical prediction.

Aerodynamic Analysis of Camber Morphing Airfoils in Transition via Computational Fluid Dynamics

“…Morphing wings enable aircraft to optimize flight mode by changing wing shapes through active adjustment of wing shapes corresponding to external or internal flight conditions while flight [ 1 , 3 , 7 , 8 , 9 , 10 ]. Most works in morphing focus on the mechanisms concerning conventional mechanical design or Smart materials and their proof-of-concept stages and material/structure-based internal mechanisms, which are far from realization and test flight of morphing aircraft [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ].…”

Comparative Aerodynamic Performance Analysis of Camber Morphing and Conventional Airfoils

“…Most of the morphing wing research works focus on either the design and implementation of morphing concepts using selected materials and structures [4][5][6][7][8][9][10][11], or the analysis Most of the morphing wing research works focus on either the design and implementation of morphing concepts using selected materials and structures [4][5][6][7][8][9][10][11], or the analysis of the structural and aerodynamic performance of suggested morphing concepts and their mechanisms [12][13][14][15]. Researchers have developed camber morphing mechanisms using smart materials [16][17][18], corrugated structures [19], multi-unit rib structures [20], vertically slitted rib structures [21], truss elements and runners [22], pressure-actuated cellular structures [23,24], bio-inspired FishBAC structures [25], monolithic compliant mechanisms [26], or combined form [27] to introduce and validate their effectively working models and design implementation. Some morphing wing design implementations were even validated with an effectively flown test model [27][28][29][30][31].…”

Parametric Study of a Composite Skin for a Twist-Morphing Wing

“…Planform morphing includes resizing the span and chord lengths and modifying the sweep angle [4]. Out-of-plane morphing includes twisting, change in dihedral angle, camber-morphing, and span-wise bending [5][6][7]. Airfoil morphing includes reshaping the airfoil profile and thickness.…”

“…With the advancements in smart materials, like shape memory alloys (SMA) and piezoelectric materials, many researchers have been developing innovative methods of incorporating smart materials and compliant structures into morphing wings [5,12,[25][26][27]. Barrett [25] showed that twist-morphing can be induced with the use of bimorph piezoelectric actuators.…”