On the multidisciplinary control and sensing of a smart hybrid morphing wing

Morphing wing technology is of great interest for improving the aerodynamic performance of future aircraft. A morphing wing prototype using both surface embedded Shape Memory Alloys (SMA) and piezoelectric macro fiber composite (MFC) actuators has been designed for wind tunnel experiments. This smart wing is a mechatronic system that contains embedded sensors to measure the surrounding flow and control the actuators. This article will focus on the control of the cambering system which is achieved using a group of nested control loops as well as on the perspective of a novel control strategy using in-situ temperature measurements. It will be shown that by exploiting the inherent hysteretic properties of the SMAs cambering a significant reduction in power consumption is possible by appropriately tailoring the control strategy. Furthermore, by comparing the post-processed pressure signals recorded during the wind tunnel experiments to the aerodynamic performance gains a perspective for a novel in-situ control will be shown

Implementation of a hybrid electro-active actuated morphing wing in wind tunnel

Amongst current aircraft research topics, morphing wing is of great interest for improving the aerodynamic performance. A morphing wing prototype has been designed for wind tunnel experiments. The rear part of the wing - corresponding to the retracted flap - is actuated via a hybrid actuation system using both low frequency camber control and a high frequency vibrating trailing edge. The camber is modified via surface embedded shape memory alloys. The trailing edge vibrates thanks to piezoelectric macro-fiber composites. The actuated camber, amplitude and frequency ranges are characterized. To accurately control the camber, six independent shape memory alloy wires are controlled through nested closed-loops. A significant reduction in power consumption is possible via this control strategy. The effects on flow via morphing have been measured during wind tunnel experiments. This low scale mock-up aims to demonstrate the hybrid morphing concept, according to actuator capabilities point of view as well as aerodynamic performance

A new prototype of piezoelectric bending resonant transducer for analysis of soft tissues properties

This paper is devoted to a new piezoelectric bending resonant transducer prototype dedicated to the characterization of the mechanical properties of soft tissue. A general description of the actuator’s structure is presented including the basic principles of the measurement. The chosen geometry of the prototype is discussed and compared with the existing version. Constitutive equations are presented for the active and passive layer of the cantilever transducer. The prototype is verified by means of finite element method analysis. Results of the static and modal analysis are presented and discussed

An experimental platform for surface embedded SMAs in morphing applications

This article will address the modeling and control of surface embedded shape memory alloys (SMAs) for the camber modification of a hybrid morphing airfoil. An analytical model will be derived. The results of this models will be discussed and compared to the experiments. The advantages of this modeling approach will be highlighted and alternatives will be briefly revisited. This discussion will figure into the utility of these models in the sizing of a full scale prototype of a SMA actuated active trailing edge of an airfoil. Throughout this article the prototype specifications are detailed and the design choices will be discussed. Performance improvements stemming from the inherent nature of the SMAs will be analyzed. It will be shown in this article that through the use of forced convection the overall cycle time can be reduced

Dynamics of a hybrid morphing wing with active open loop vibrating trailing edge by Time-Resolved PIV and force measures

A quantitative characterization of the effects obtained by high frequency-low amplitude trailing edge actuation is presented. Particle image velocimetry, pressure and aerodynamic forces measurements are carried out on a wing prototype equipped with shape memory alloys and trailing edge piezoelectric-actuators, allowing simultaneously high deformations (bending) in low frequency and higher-frequency vibrations. The effects of this hybrid morphing on the forces have been quantified and an optimal actuation range has been identified, able to increase lift and decrease drag. The present study focuses more specifically on the effects of the higher-frequency vibrations of the trailing edge region. This actuation allows manipulation of the wake turbulent structures. It has been shown that specific frequency and amplitude ranges achieved by the piezoelectric actuators are able to produce a breakdown of larger coherent eddies by means of upscale energy transfer from smaller-scale eddies in the near wake. It results a thinning of the shear layers and the wake's width, associated to reduction of the form drag, as well as a reduction of predominant frequency peaks of the shear-layer instability. These effects have been shown by means of frequency domain analysis and Proper Orthogonal Decomposition

Shape control and design of aeronautical configurations using shape memory alloy actuators

The paper proposes an efficient methodology that allows to design smart deformable aeronautical configurations that are able to achieve pre-defined target shapes by adjusting the temperature of Shape Memory Alloy (SMA) actuators. SMA-based actuation finds extensive application in morphing concepts which are adopted in aeronautics to enhance the aerodynamic performance by continuously varying the geometry of the wing. A novel robust algorithm, developed for predicting the nonlinear response of the SMA-structure interaction problem is presented. The algorithm is coupled with an optimization method in order to predict the optimal structural and operational parameters with respect to target shapes of the controlled configuration. The design methodology presented in this study selects the design parameters of the problem at hand, i.e. the location of the actuators and the operating temperature, for given loading conditions. The proposed methodology is validated and demonstrated with three case studies, including the design of a real-world aeronautical configuration

Trailing-edge dynamics of a morphing NACA0012 aileron at high Reynolds number by high-speed PIV

Particle image velocimetry (piv) measurements are made at the trailing edge of a piezoelectric actuated aileron in order to investigate the physical effect on the flow via high-frequency low-amplitude actuation at high Reynolds numbers. The measurements at different actuation frequencies show the modification of the primary frequency components of the flow with the actuation frequency. A statistical analysis reveals the reduction of the Reynolds stress components which increases with the actuation frequency. Proper orthogonal decomposition (pod) analysis shows the modification of the spatial modes illustrating the vortex breakdown in the shear-layer and the reduction of the temporal mode spectral energy depending on the actuation. It has been shown that a specific low amplitude actuation frequency produces a significant reduction of the predominant shear-layer frequency

Trailing-edge dynamics and morphing of a deformable flat plate at high Reynolds number by time-resolved PIV

The present paper investigates the turbulent wake structure in the near-region past the trailing edge of a deformable inclined plate. The plate is actuated by shape memory alloys. Using these actuators a significant deformation (bending) can be achieved (≈10%≈10% of the chord) under the aerodynamic loads corresponding to a Reynolds number of 200 000. The shear-layer dynamics as well as the mean velocity and turbulent stresses have been quantified for a reference case (flat plate inclined at 10°). The present study investigates the modification of the shear-layer and near-wake dynamics achieved by means of the dynamic deformation of the plate compared with static cases that include three intermediate positions of the deformed plate. The comparison of the static cases with the dynamic regime discusses the validity of the quasi-static hypothesis for the present low frequency actuation. It is found that the present actuation enhances the shearing mechanisms past the trailing-edge and modifies the von-Kármán mode as well as the structure of the shear-layer, Kelvin–Helmholtz eddies. Moreover, the increase of the bending enhances the appearance of the pairing mechanism between successive shear-layer eddies and the interaction between the von-Kármán and shear-layer instability modes. Furthermore, it has been found that the increase of the plate׳s curvature leads to an attenuation of the shear-layer amplitude and of the overall spectral energy, concerning the most deformed positio

A combined smart-materials approach for next-generation airfoils

This article will present a morphing wing actuated using both surface embedded Shape memory alloys (SMAs) and trailing edge Macro-fiber composites (MFCs). This combination enables the airfoil to simultaneously achieve large scale deformations at low frequencies as well as rapid actuation with a limited amount of displacement. Thereby not only can the shape of the airfoil be optimized in function of the current mission profile but also the shear layer can be influenced. Each actuator is modelled using both a finite element and/or an analytical model and the results will be verified experimentally