SMA actuators for morphing wings

International Conference on Informatics in Control, Automation and Robotics, 2010

The paper represents the second part of a study related to the development of an actuators control system for a morphing wing application, and describes the experimental validation of the control designed in the first part. After a short presentation of the finally adopted control architecture, the physical implementation of the control is done. To implement the controller on the physical model two Programmable Switching Power Supplies AMREL SPS100-33 and a Quanser Q8 data acquisition card, were used. The inputs of the data acquisition were two signals from Linear Variable Differential Transformer potentiometers, indicating the positions of the actuators, and six signals from thermocouples installed on the SMA wires. The acquisition board outputs channels were used to control power supplies in order to obtain the desired skin deflections. The control validation was made in two experimental ways: bench test and wind tunnel test. All 35 optimized airfoil cases, used in the design phase, were converted into actuators vertical displacements which were used as inputs reference for the controller. In the wind tunnel tests a comparative study was realized around of the transition point position for the reference airfoil and for each optimized airfoil.

2010

The paper represents the second part of a study related to the development of an actuators control system for a morphing wing application, and describes the experimental validation of the control designed in the first part. After a short presentation of the finally adopted control architecture, the physical implementation of the control is done. To implement the controller on the physical model two Programmable Switching Power Supplies AMREL SPS100-33 and a Quanser Q8 data acquisition card, were used. The inputs of the data acquisition were two signals from Linear Variable Differential Transformer potentiometers, indicating the positions of the actuators, and six signals from thermocouples installed on the SMA wires. The acquisition board outputs channels were used to control power supplies in order to obtain the desired skin deflections. The control validation was made in two experimental ways: bench test and wind tunnel test. All 35 optimized airfoil cases, used in the design phase, were converted into actuators vertical displacements which were used as inputs reference for the controller. In the wind tunnel tests a comparative study was realized around of the transition point position for the reference airfoil and for each optimized airfoil.

Smart Materials and Structures, 2014

Shape memory alloys (SMAs) are a unique class of metallic materials with the ability to recover their original shape at certain characteristic temperatures (shape memory effect), even under high applied loads and large inelastic deformations, or to undergo large strains without plastic deformation or failure (super-elasticity). In this review, we describe the main features of SMAs, their constitutive models and their properties. We also review the fatigue behavior of SMAs and some methods adopted to remove or reduce its undesirable effects. SMAs have been used in a wide variety of applications in different fields. In this review, we focus on the use of shape memory alloys in the context of morphing aircraft, with particular emphasis on variable twist and camber, and also on actuation bandwidth and reduction of power consumption. These applications prove particularly challenging because novel configurations are adopted to maximize integration and effectiveness of SMAs, which play the role of an actuator (using the shape memory effect), often combined with structural, load-carrying capabilities. Iterative and multidisciplinary modeling is therefore necessary due to the fluid-structure interaction combined with the nonlinear behavior of SMAs.

INCAS BULLETIN, 2012

For this study, the upper surface of a rectangular finite aspect ratio wing, with a laminar airfoil cross-section, was made of a carbon-Kevlar composite material flexible skin. This flexible skin was morphed by use of Shape Memory Alloy actuators for 35 test cases characterized by combinations of Mach numbers, Reynolds numbers and angles of attack. The Mach numbers varied from 0.2 to 0.3 and the angles of attack ranged between -1° and 2°. The optimized airfoils were determined by use of the CFD XFoil code. The purpose of this aeroelastic study was to determine the flutter conditions to be avoided during wind tunnel tests. These studies show that aeroelastic instabilities for the morphing configurations considered appeared at Mach number 0.55, which was higher than the wind tunnel Mach number limit speed of 0.3. The wind tunnel tests could thus be performed safely in the 6'×9' wind tunnel at the Institute for Aerospace Research at the National Research Council Canada (IAR/NRC), where the new aeroelastic studies, applied on morphing wings, were validated.

AIAA Atmospheric Flight Mechanics Conference, 2011

The main objectives of this research work are: the design and the wind tunnel testing of a controller for a new morphing mechanism using smart materials made of Shape Memory Alloy (SMA) for the actuators, and the aero-elasticity studies for the morphing wing. The finally obtained configuration for the controller is a combination of a bi-positional controller (on-off) and a PI (proportional-integral) controller, due to the two phases (heating and cooling) of the SMA wires' interconnection. Firstly, the controller is used for the open loop development step of a morphing wing project, while, further, it is included as an internal loop in the closed loop architecture of the morphing wing system. In the controller design procedure four step are considered: 1) SMA actuators model numerical simulation for different loading force cases; 2) linear system approximation in the heating and cooling phases using Matlab's System Identification Toolbox and the numerical values obtained in the first step; 3) selecting the controller type and its tuning for each of the two SMA actuators' phasesheating and cooling; and 4) integration of the two controllers just obtained into a single controller. For the controller validation three actions are taken: 1) numerical simulation; 2) bench testing; and 3) wind tunnel testing. For the third part of this study, aeroelastic studies, the purpose is to determine the flutter conditions in order to be avoided during wind tunnel tests. These studies show that aeroelastic instabilities for the morphing configurations considered appears at Mach number 0.55, which is higher than the wind tunnel Mach number limit speed of 0.3.

Journal of Materials Engineering and Performance, 2009

The adaptive structures concept is of great interest in the aerospace field because of the several benefits which can be accomplished in the fields including noise reduction, load alleviation, weight reduction, etc., at a level in which they can be considered as compulsory in the design of future aircraft. Improvements in terms of the aerodynamic efficiency, aeroelastic behavior, stability, and manoeuvrability performance have already been proved through many international studies in the past. In the family of the Smart Materials, Shape Memory Alloys (SMA) seem to be a suitable solution for many static applications. Their high structural integrability in conjunction with actuation capabilities and a favorable performance per weight ratio, allows the development of original architectures. In this study, a morphing wing trailing edge concept is presented; morphing ability was introduced with the aim of replacing a conventional flap device. A compliant rib structure was designed, based on SMA actuators exhibiting structural potential (bearing external aerodynamic loads). Numerical results, achieved through a FE approach, are presented in terms of trailing edge induced displacement and morphed shape.

Journal of Theoretical and Applied Mechanics, 2014

DSC tests were performed on several types of SMAs to verify the phase-transformation temperatures, and then experiments to examine their characteristics were carried out. An electric-current was supplied to the SMA wire to measure the appropriate operational current range. The force generated by the SMA wire increased according to the supplied current, but it diminished when the over-current was supplied because thermo-mechanical properties of the wire started to degrade. The appropriate stress range for effective actuation characteristics was also investigated. The SMA wire actuator was designed to operate a morphing wing. Experiments for the wing were conducted to verify its characteristics and it was smoothly deformed.

Materials Today: Proceedings, 2018

The term morphing is used in matters of planes that undergo pre-intended structural changes in order to meet the required role specifications. Wing morphing results in varied advantages like increased speed, roll control, reduced power consumption, etc. But the morphing associated issues such as surface discontinuity and overweight of control structures can only be overcome with the use of smart materials and their corresponding mechanisms. In order to illustrate the use of smart materials to achieve morphing a case study of camber change for the horizontal tail of an unmanned aerial vehicle through shape memory alloys is presented in this article. Shape-memory polymers (SMPs) have the ability to return from a deformed state to their original shape induced by an external stimulus, such as temperature change. The numerical analysis conducted considering point loads incorporating the shape memory effect yielded a deflection of 0.6mm at trailing edge of the HT.

Mechatronics, 2014

In this work, a two degree-of-freedom (DOF) mechanism is designed and fabricated that is appropriate for morphing wing applications. The mechanism is developed in such a way that it can undergo different two degrees of freedom so that the wing can have more efficient maneuvers. Among the smart materials Shape Memory Alloy (SMA) actuators are capable of providing more efficient mechanisms in comparison with the conventional actuators due to their large force to stroke ratio, smaller size with high capabilities in limited spaces, and lower weight. As SMA wires have nonlinear hysteresis behavior, their modeling should be implemented in a meticulous way. In this research, after proposing a two DOF morphing wing, a modification is done on a well-known model of SMA, and then the mechanism is modeled. The numerical results of the model simulation are verified against the experimental results using a test setup to validate the proposed model prediction. The proposed mechanism is fabricated in order to verify the model with experimental data. The comparison between theoretical and experimental results shows that the experimental results have good agreement with the theoretical results.

In this paper, the design methodology and test results of a morphing wing controller are presented. Bench tests on optimized airfoils at various Mach numbers, angles of attack and Reynolds numbers were performed at the LAMSI laboratory. A rectangular finite aspect ratio wing having a morphing airfoil cross section due to a flexible skin installed on the wing upper surface was instrumented with two shape memory alloys actuators which created the two control points displacements on the flexible skin in order to realize the optimized airfoil shapes. These optimized airfoils were previously calculated for each airflow condition as a combination of angles of attack and Mach numbers such that the transition point position was found to be the nearest possible to the trailing edge. In the bench tests, the airfoil shapes were scanned by use of a laser beam. Then, the scanned airfoils were compared to the sets of theoretical optimized airfoils and to the sets of simulated airfoils using the finite element method model.