CEAS/AIAA/ICASE/NASA Langley International Forum on Aeroelasticity and Structural Dynamics 1999

The proceedings of a workshop sponsored by the Confederation of European Aerospace Societies (CEAS), the American Institute of Aeronautics and Astronautics (AIAA), the National Aeronautics and Space Administration (NASA), Washington, D.C., and the Institute for Computer Applications in Science and Engineering (ICASE), Hampton, Virginia, and held in Williamsburg, Virginia June 22-25, 1999 represent a collection of the latest advances in aeroelasticity and structural dynamics from the world community. Research in the areas of unsteady aerodynamics and aeroelasticity, structural modeling and optimization, active control and adaptive structures, landing dynamics, certification and qualification, and validation testing are highlighted in the collection of papers. The wide range of results will lead to advances in the prediction and control of the structural response of aircraft and spacecraft

Contributions to aerostructures morphing with piezoelectric actuators

Since the first models developed in the late 19th century, the applications of piezoelectric materials have been progressively growing in number. The capacity of these materials to couple electric and mechanic fields makes them perfect candidates in the study of geometrical morphing. Their application in aeronautical products has been traditionally seen from two different perspectives: their use as sensors and as actuators. Both functions present potential benefits and improvements with promising applications. While the investigations in the past years focused mainly in the analysis and integration of piezoelectric materials in structures as means of implementing what is known as structural health monitoring systems, the application of this type of materials as actuators in the geometrical control of structures also awakes interest in the scientific community. In its present state of development, the technology for morphing of structures using piezoelectric actuators is not yet advanced enough as to integrate such systems in commercial products. However, the field is in continuous development and the evolution of the materials and the integration solutions bring the technology closer to industrial application. This thesis aims at studying the feasibility of application of piezoelectric-actuated morphing aeronautical structures in current aircraft concepts. The analysis is performed at theoretical and experimental levels analyzing the static and dynamic performance of currently available actuators and motion amplification technologies. The research presented in this thesis is directed in two different applications of utilization of the actuators: as static actuators producing deformation of the aerodynamic surface and as dynamic actuators controlling a classic aerodynamic control surface. In each of the applications a different type of piezoelectric actuator architecture has been used: a piezoelectric patch has been selected for static morphing applications and a piezoelectric stack-based actuation system for the dynamic control of the conventional control surface. The static experiments performed aimed at demonstrating the suitability of piezoelectric actuators as morphing devices. This analysis was performed analyzing the deflections produced in the trailing edge of an aerodynamic profile. The analysis of the obtained experimental results showed promising results as the actuating configurations managed to perform as designed. The static experiments showed substantial deformation of the trailing edge of the wing profile making this configuration mature enough for further experimentation such as wind tunnel testing. The deflections produced were, however, not significant enough for the direct application of the solution into larger scale configurations. Scalability of the technological solutions remains one of the major challenges of the technology in the morphing applications. The dynamic results showed good performance of the actuators in an anti-flutter demonstrator application during wind tunnel testing. The experiments showed that the system remained stable well passed the flutter velocity; this allows for further experimentation in structures presenting higher flutter speeds. With the development of the next generation of advanced piezoelectric ceramics, with piezoelectric coefficients twice as large in comparison to PZT-based ceramics, the application of the deforming structure concept is very promising for application in larger demonstrators in both static and dynamic applications. The next generation of piezoelectric materials presents itself as a first step into a solution to the scalability of the technology for application into full-scale demonstrators.Des dels primers models desenvolupats durant el segle XIX, les aplicacions per a materials piezoelèctrics han anat creixent progressivament. La relació que presenten aquests materials entre el comportament mecànic i el comportament elèctric els converteix en candidats ideals en l'estudi d'estructures deformables. L'aplicació de piezoelèctrics en aeronàutica es concep tradicionalment des de dues perspectives: com a sensors o com a actuadors. Ambdues presenten potencials beneficis i aplicacions. Tot i que en els últims anys la recerca s'ha concentrat en l'estudi d'integració dels materials en sistemes que permeten controlar la salut de l'estructura (Structural Health Monitoring), l'aplicació de piezoelèctrics com a actuadors d'estructures deformables desperta l'interès de la comunitat científica. En l'estadi actual, la tecnologia necessària per deformar estructures de forma controlada utilitzant materials piezoelèctrics no està suficientment desenvolupada. No obstant, la recerca en aquest camp està en continu desenvolupament i s'apropa a solucions que permetran integrar-la en aplicacions industrials. L'objectiu de la tesi és estudiar la possibilitat d'utilitzar deformacions produïdes mitjançant actuadors piezoelèctrics en estructures aeronàutiques actuals. L'anàlisi està orientat des de punts de vista teòric i experimental i es centra en el comportament estàtic i dinàmic de solucions tecnològiques amb actuadors i tecnologies d'amplificació disponibles comercialment. La recerca que es presenta en la tesi estudia dues aplicacions diferents en l'ús d'aquest tipus d'actuadors: com a actuadors en regim estàtic, produint deformacions de la superfície aerodinàmica, i com a actuadors dinàmics, que controlin una superfície de control convencional. L'arquitectura de la solució tecnològica emprada ha estat diferent en cada aplicació: en la deformació estàtica de la superfície aerodinàmica l'actuador és de tipus "patch" mentre que en el cas dinàmic és de tipus "stack". Els experiments estàtics desenvolupats tenen com a objectiu demostrar la capacitat dels piezoelèctrics com a elements que produeixin deformacions en l'estructura (morphing). Aquest objectiu es demostra analitzant les deflexions produïdes en el caire de fuga d'un perfil aerodinàmic. Els resultats experimentals obtinguts són optimistes ja que les diferents configuracions d'actuadors es comporten tal i com prediuen els models. En règim estàtic, les deformacions produïdes en el caire de fuga son substancials. Això permet assegurar que la configuració utilitzada en els experiments és prou madura com per seguir investigant, per exemple, en túnel de vent. Malgrat això, les deformacions produïdes encara no són suficientment significatives com per integrar l'experiment en un model més gran. L'escalabilitat és un dels reptes més importants que presenta la tecnologia en aplicacions de "morphing". Els resultats dinàmics demostren una bona actuació de l'actuador integrat en un sistema anti-flameig en els experiments en túnel de vent. Els experiments demostren la capacitat del sistema de mantenir-se estable a velocitats mes enllà de l'aparició del flameig. El següent pas en aquesta línia de recerca es l'investigació en models més complexos en quant a aparició de flameig. Amb el desenvolupament d'una nova generació de materials piezoelèctrics ceràmics avançats, que promet coeficients piezoelectrics el doble d'alts en comparació amb els materials basats en PZT disponibles actualment, l'arquitectura experimentada en règim estàtic és un molt bon candidat en aplicacions a escala més gran. Aquesta propera generació de materials es presenta com un primer pas en solucionar els problemes d'escalabilitat que presenta la tecnologia actualment

Acoustic and Elastic Waves: Recent Trends in Science and Engineering

The present Special Issue intends to explore new directions in the field of acoustics and ultrasonics. The interest includes, but is not limited to, the use of acoustic technology for condition monitoring of materials and structures. Topics of interest (among others): • Acoustic emission in materials and structures (without material limitation) • Innovative cases of ultrasonic inspection • Wave dispersion and waveguides • Monitoring of innovative materials • Seismic waves • Vibrations, damping and noise control • Combination of mechanical wave techniques with other types for structural health monitoring purposes. Experimental and numerical studies are welcome

Large space structures and systems in the space station era: A bibliography with indexes (supplement 04)

Bibliographies and abstracts are listed for 1211 reports, articles, and other documents introduced into the NASA scientific and technical information system between 1 Jul. and 30 Dec. 1991. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

Aeronautical engineering: A continuing bibliography with indexes (supplement 321)

This bibliography lists 496 reports, articles, and other documents introduced into the NASA scientific and technical information system in Sep. 1995. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics

Aeronautical engineering: A continuing bibliography with indexes (supplement 282)

This bibliography lists 623 reports, articles, and other documents introduced into the NASA scientific and technical information system in Aug. 1992. The coverage includes documents on the engineering and theoretical aspects of design, construction, evaluation, testing, operation, and performance of aircraft (including aircraft engines) and associated components, equipment, and systems. It also includes research and development in aerodynamics, aeronautics, and ground support equipment for aeronautical vehicles

Aeronautical engineering: A continuing bibliography with indexes (supplement 301)

This bibliography lists 1291 reports, articles, and other documents introduced into the NASA scientific and technical information system in Feb. 1994. Subject coverage includes: design, construction and testing of aircraft and aircraft engines; aircraft components, equipment, and systems; ground support systems; and theoretical and applied aspects of aerodynamics and general fluid dynamics