Johannes Scheller

Hybrid Electroactive Wings Morphing for Aeronautic Applications

As part of the RTRA funded EMMAV (Electroactive Morphing for Micro-Airvehicles) research program electroactive materials were studied as well as their applications as actuators for morphing wings. The aim of this research program is to study both the actuation with large displacements at low frequencies as well as low displacement, high frequency actuation. The large displacement actuation, which targets primarily the flight control, is achievable using Shape Memory Alloys (SMA) while high frequency; low displacement actuation can be achieved using piezoelectric actuators [. This high frequency actuation is especially interesting for improving the aeroelastic coupling effect inducing both noise and drag. This paper describes the construction of a prototype incorporating piezoelectric and SMA based actuation mechanisms. Furthermore, a cooling mechanism for SMAs is described aiming at improving the cycle time of the actuator. The developed prototype is to be evaluated during wind-tunnel experiments showing the influence of the actuation on the fluid.

A hybrid morphing NACA4412 airfoil concept

This paper details the design and development of a hybrid actuator system combining surface actuated Shape memory alloys (SMAs) and trailing-edge Macro fibre composites (MFCs) for a NACA 4412 airfoil. This design allows both for a high-frequent (≈ 100 Hz) low-displacement actuation as well as a low-frequent large-displacement actuation. The design of the actuator system is highlighted, the simulation model is described and the test-setup is illustrated. Preliminary results are promising regarding the control of the desired lift.

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.

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.

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.