Optimization and integration of shape memory alloy (SMA)-based elastic actuators within a morphing flap architecture

Abstract

Aircraft morphing architectures are currently worldwide investigated to enhance performance while reducing weights, volumes and costs. A 3-flap wing, for instance, shall pay a penalty up to 100% due to the insertion of mechanical devices in its body. Moreover, the insertion of cover nacelles disturbs the wing aerodynamics itself. In addition, flapped wings are noisy: deformable, instead of slotted and flapped wings, may lead to significant enhancement also in this field. Within Joint European Initiative on Green Regional Aircraft frame, in cooperation with the University of Naples, Department of Aerospace Engineering, the authors with their colleagues came to the definition of dedicated morphing architectures. This paper focuses on the design and optimization of a morphing architecture based on Shape Memory Alloy (SMA) technology, aimed at increasing airfoil trailing edge curvature. The deformable rib system is constituted of four elastic elements. The aerodynamic loads were computed through a classical panel method for the most severe flight condition. The descriptive finite element model underwent an optimization process performed through a proprietary code, based on a genetic selection strategy. Resulting values, from the optimization study were different for the variables referring to each subsystem: plate thickness, depth and length, relative orientation, SMA ribbons thickness, depth and location. Trailing edge vertical displacement was assumed as target. The main features of the 4 elastic elements are presented in the body of the document. As expected, the more rearward is the element position, the less is the weight and size; decreasing values of the aerodynamic load led towards lighter solutions.

Fuzzy Logic-Based Control for a Morphing Wing Tip Actuation System: Design, Numerical Simulation, and Wind Tunnel Experimental Testing

“…Forty-nine rules for the "SpeedFIS" (Figure 11), and four rules for the "Current FIS": Starting from the inputs' and output's membership functions of the three FISs, a set of sec inference rules were obtained for the "PositionFIS": Rule 1 : I f in1 is A 1 1 and in2 is A 1 2 , then y 1 (in1, in2) = −3000, Rule 2 : I f in1 is A 2 1 and in2 is A 2 2 , then y 2 (in1, in2) = −2500, Rule 3 : I f in1 is A 3 1 and in2 is A 3 2 , then y 3 (in1, in2) = −1000, Rule 4 : I f in1 is A 4 1 and in2 is A 4 2 , then y 4 (in1, in2) = 1000, Rule 5 : I f in1 is A 5 1 and in2 is A 5 2 , then y 5 (in1, in2) = 2500, Rule 6 : I f in1 is A 6 1 and in2 is A 6 2 , then y 6 (in1, in2) = 3000,…”

Design of SMA-Based Structural Actuators

“…9 The chromosomes/design parameters taken into account and the variation ranges are reported in Table 9.4. In this section, a more general approach is described, and the radius of the arc, the thickness laws in the radial and transversal directions, and the dimensions of the SMA ribbon are taken into account.…”

“…9 The device is comprised of a supporting metallic structure made of two crossed beams in the shape of an X (components 1 and 2); these beams are clamped on the left and linked rigidly to each other on the right (AB line). This actuator is aimed at producing the deformation of a morphing architecture of the trailing edge.…”

Distributed actuation concepts for a morphing aileron device

“…Actuation is carried out via a lever mechanism driven by load-bearing actuators that combine load-carrying and actuation capacities. Fewer actuators are typically required to control the morphing structure and the overall advantages derive from the reduced mass, volume, force and consumed power (11)(12)(13)(14) .…”