Smart material actuator for trailing edge thickening

Botha, Theuns (2016-03)

Thesis (MEng)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: The goal of the research project is to provide the conceptual, high level and subsystem level design of an actuation system that would achieve a shape change at the trailing edge of the rudder of a next generation Airbus aircraft. The shape change should be from blunt to a sharp form and vice versa. The purpose of the shape change is to increase the low-speed lift of the vertical tail wing: a strategy proposed by Airbus Future Programmes, following aerodynamic research conducted by them. The increased lift would allow for a reduction in the size of the vertical tail wing, but an increase in aerodynamic drag would result from the blunt trailing edge. This trade-off between the lift and the drag characteristics is what drives the need for bi-directional actuation. The challenge is to design an actuation mechanism that would it inside the confined space at the trailing edge. Since the typically used hydraulic actuators and their supporting systems are normally too bulky for such a confined space, the use of alternative technologies such as smart materials is explored. The benefit of the research is that the reduction of the tail wing size would lead to lower in-flight drag as well as a reduction in the overall mass of the aircraft. The research followed a systemic hardware development process, consisting of a requirements capture, conceptual design and detailed design, as well as implementation and verification phases. The design requirements were captured interactively with technical specialists from Airbus. Different system concepts were generated and compared in a pareto trade-off study, and Shape Memory Alloy (SMA) technology was identified as the technology most suited to the application. The feasibility of the concept design was then explored through the design, manufacturing and practical testing of a prototype actuator. The actuator design was based on a parallel arm architecture, and included special links that provided lateral stabilisation. Both the architecture and the stabilisers proved effective, but the manner in which the SMA wires are employed still needs to be refined.

AFRIKAANSE OPSOMMING: Die doel van hierdie navorsingsprojek is om die konseptuele, stelsel-vlak sowel as substelselvlak ontwerp uit te voer vir n aktueringstelsel wat die sleepkant van n vliegtuig roer se vorm moet aanpas. Die verandering in vorm moet wissel tussen n verdikking aksie in een rigting, en n verdunning aksie in die ander. Die verdikking se funksie is om n verhoging in stygkrag te bewerkstellig, soos voorgestel deur Airbus Future Programmes. Hierdie voorstel het gevolg na aerodinamiese analises wat deur hulle voltooi is. Die gevolg van verbeterde stu-krag is dat die vlerke verklein kan word om sodoende die massa en brandstof verbruik van die vliegtuig verlaag. Alhoewel daar n verhoging in stygkrag geskied is dit slegs voordelig tydens lae-spoed vlug, siende dat die sleepkant-verdikking gepaard gaan met n verhoging in die ho-spoed sleurkrag van die vlerk. Hierdie teenstrydigheid in behoeftes tussen lae en ho-spoed vlug is die rede waarom die aktueerder in twee rigtings moet kan funksioneer. Wat hierdie ontwerp uitdagend maak is die feit dat die sisteem in n baie beperkte volume moet pas, n volume wat moontlik te klein is vir die lomp hidroliese aktueerders wat oor die algemeen in lugvaart-sisteme gebruik word. Daar word vermoed dat moderne aktuerings-tegnologië , genaamd "smart materials", voordele kan inhou in hierdie verband. Dus word hierdie tegnologi tydens die navorsing as sterk kandidate beskou. Die navorsing volg n sistematiese, gestruktureerde benadering van hardeware ontwerp. Hierdie ontwerpsproses sluit in die bepaling van die sisteem se behoeftes, n konsep ontwerp en n gedetaileerde ontwerp, asook implimentering en verifiring van n aktueerder prototipe. Die behoefte bepaling is gedoen met insae van Airbus. In die konsep ontwerp is verskeie konsepte teen mekaar opgeweeg, waardeur bepaal is dat Shape Memory Alloys (SMA)die mees gepaste tegnologie is vir die betrokke projek. Deur die konsep te ontwikkel tot n fisiese prototipe, en hierdie prototipe aan n eksperimentele proses bloot te stel, is die lewensvatbaarheid van die konsep ondersoek. Tydens hierdie ontwikkeling is daar besluit op n parallele argitektuur vir die strukturele komponente, en dele van die struktuur is so uitgel dat dit die laterale stabiliteit van die meganisme bevoordeel. Daar is bevind dat die parallele argitektuur effektief die las versprei, en dat laterale stabiliteit wel deur die betrokke komponente bewerkstellig is. Die gebruik van die SMA materiaal moet egter verder ondersoek word indien daar gepoog wil word om dit optimaal te benut

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/98757
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