1,721,059 research outputs found
CLEAN SKY - GRA, LOW NOISE CONFIGURATION DOMAIN (phase 1)
No full textThe Clean Sky is one of the Joint Technology Initiatives (JTI) launched by the EC in the FP8. It represent the most ambitious research program in Europe (approximate value: 1.6 B€) aiming at the greening of Aeronautics and Air Transport; 30-40% reduction of CO2 and NOX emissions and the halving of perceived noise around airports are both pursued through the integration of advanced technologies; validation of results is expected to be achieved in a multidisciplinary approach leading to full-scale ground and flight demonstrators.
Technologies allowing for such step change are organized into six main themes, six Integrated Technology Demonstrators (ITD), that cover the broad range of R&T work. A "technological evaluator" - a set of models to predict the local and global ecological impact of the technologies being integrated - will allow independent analysis of the projects results as they unfold. The “Low Noise Configuration” project within the GRA ITD is pursuing a dual purpose:
to assess technologies aimed at reducing airframe noise which during approach and landing phases (with engine power at minimum, high-lift devices deployed and undercarriage lowered) is a major contributor to the aircraft annoyance perceived by the resident population;
to address technology innovation toward other paramount functions for a next generation, green regional aircraft:
highly-efficient aerodynamics, including a Natural Laminar Flow (NLF) wing concept, to reduce fuel consumption and pollution at cruise condition;
wing loading control to enhance aerodynamic efficiency in all flight conditions and, hence, to reduce fuel consumption and pollution over the whole mission also allowing for steeper initial climb, noise-abatement flight trajectories;
wing loading alleviation to avoid any possible loads exceeding over structural design conditions and, hence, to optimize the wing structural design for weight savings.
The domain work programme develops through several phases: from the definition of requirements & architectures (phase 1), through the assessment of enabling technologies and subsequent application studies , up to the final demonstrations (phase 2 and 3) of selected solutions
CLEAN SKY - GRA, LOW NOISE CONFIGURATION DOMAIN (phases 2 and 3)
No full textThe Clean Sky is one of the Joint Technology Initiatives (JTI) launched by the EC in the FP8. It represent the most ambitious research program in Europe (approximate value: 1.6 B€) aiming at the greening of Aeronautics and Air Transport; 30-40% reduction of CO2 and NOX emissions and the halving of perceived noise around airports are both pursued through the integration of advanced technologies; validation of results is expected to be achieved in a multidisciplinary approach leading to full-scale ground and flight demonstrators.
Technologies allowing for such step change are organized into six main themes, six Integrated Technology Demonstrators (ITD), that cover the broad range of R&T work. A "technological evaluator" - a set of models to predict the local and global ecological impact of the technologies being integrated - will allow independent analysis of the projects results as they unfold. The “Low Noise Configuration” project within the GRA ITD is pursuing a dual purpose:
to assess technologies aimed at reducing airframe noise which during approach and landing phases (with engine power at minimum, high-lift devices deployed and undercarriage lowered) is a major contributor to the aircraft annoyance perceived by the resident population;
to address technology innovation toward other paramount functions for a next generation, green regional aircraft:
highly-efficient aerodynamics, including a Natural Laminar Flow (NLF) wing concept, to reduce fuel consumption and pollution at cruise condition;
wing loading control to enhance aerodynamic efficiency in all flight conditions and, hence, to reduce fuel consumption and pollution over the whole mission also allowing for steeper initial climb, noise-abatement flight trajectories;
wing loading alleviation to avoid any possible loads exceeding over structural design conditions and, hence, to optimize the wing structural design for weight savings.
The domain work programme develops through several phases: from the definition of requirements & architectures (phase 1), through the assessment of enabling technologies and subsequent application studies , up to the final demonstrations (phase 2 and 3) of selected solutions
TIVANO - Tecnologie Innovative per Velivoli di Aviazione generale di Nuova generaziOne
No full textIl progetto di ricerca si pone l’obiettivo di sviluppare alcune tecnologie individuate come chiave per il mantenimento di una posizione di “leadership” internazionale dell’industria aeronautica.
In particolare, si è posto il fuoco su due principali ambiti di applicazione: i velivoli senza pilota per l’osservazione e il monitoraggio del territorio e l’aviazione generale / addestramento primario. Tali ambiti di applicazione sono significativi perché fanno riferimento a due segmenti di mercato importanti per l’aeronautica italiana. I velivoli senza pilota rappresentano la nuova opportunità che i mercati presentano ed in generale il campo di applicazione delle tecnologie di automazione in ambito aeronautico sia militare che civile. L’aviazione generale è invece il mercato storico delle aziende nazionali i cui prodotti richiedono ora una significativa dose di innovazione per tornare ad essere competitivi.
Si sono individuate tre tecnologie fondamentali, trasversali ai due ambiti di applicazione, che si svilupperanno nel progetto.
Tali tecnologie sono:
• Propulsioni alternative alla tradizionale soluzione di motore a combustione interna alimentato ad AvGas (diesel, ibrido)
• Materiali compositi a basso costo (tecnologie di progettazione e manufacturing)
• Sistema frenante“brake by wire”
Relativamente alla propulsione si intendono indagare due importanti alternative alle soluzioni tradizionali. Da un lato si vuole perseguire la soluzione di motorizzazione diesel, da sviluppare per ottenere il rispetto dei requisiti di peso, che consentirebbe come risultato di minima l’uniformazione al combustibile impiegato dalla maggioranza dei velivoli (Jet A1) e, in prospettiva, l’impiego di tutte le soluzioni eco-compatibili attualmente in sviluppo nel mondo aeronautico.
La motorizzazione diesel rappresenta per le applicazioni APR MALE (Aeromobili a Pilotaggio Remoto Medium Altitude Long Endurance) una delle soluzioni che permette, grazie ai bassi consumi il raggiungimento di elevate caratteristiche di Endurance/Persistenza. Dall’altro lato, con una soluzione ibrida si cerca un deciso passo verso l’impiego dell’energia elettrica, coerente con tutti i trend internazionali di aumento dell’efficienza, della sicurezza e di riduzione dell’inquinamento.
In relazione ai materiali compositi, invece, si sente la necessità di sviluppare soluzioni, sia in termini di materiali che di processi produttivi e di assemblaggio, che siano specificatamente concepite per gli ambiti di applicazione individuati. Ciò significa trovare la giusta soluzione che consenta il rispetto delle stringenti normative aeronautiche ad un costo e a pesi che siano competitivi nei mercati di riferimento individuati.
Infine, l’idea di un impianto frenante “brake by wire” con attuazione completamente elettrica nasce da tre importanti obiettivi/necessità: la riduzione di complessità e pesi della piattaforma in un’ottica di soluzioni More Electric Aircraft perseguita eliminando l’impianto idraulico del sistema frenante; la possibilità di introdurre sistemi di frenata assistita e antiskid attualmente non disponibili sulla classe di velivoli target; la necessità di comandare il sistema via computer, o comunque remotamente, per le piattaforme “unmanned”; non trascurabile inoltre l’intrinseca sicurezza di un sistema elettrico rispetto ad un sistema idraulico
Oltre agli sviluppi nelle tre tematiche tecnologiche indicate, il progetto di ricerca si pone altri due importanti obiettivi realizzativi.
Il primo è relativo allo sviluppo ed implementazione di innovative metodologie di progettazione aeromeccanica che consentano di ottimizzare, secondo i requisiti prestazionali richiesti e sulla base delle esigenze strutturali, la configurazione della piattaforma di riferimento.
Il secondo obiettivo è invece più squisitamente legato all’integrazione delle tecnologie entro un dimostratore che sia progettato secondo i più moderni dettami aeronautici.
Per la dimostrazione delle tecnologie da sviluppare entro il progetto si prevedono infatti diversi livelli a seconda del “Technology Readiness Level” - di partenza. Pertanto, la dimostrazione/validazione delle varie tecnologie sarà effettuata attraverso l’utilizzo di opportuni “rig” a terra e/o dimostratore che possa andare in volo in base al “target” tecnologico di maturità ipotizzato all’inizio del progetto
SMA for Aeronautics
No full textThe aviation industry has achieved drastic improvements during the past few decades, thanks to research efforts and advances in technology. With increased emphasis on adaptability and multifunctionality, smart materials and adaptive structures are now common terms in the literature and have been investigated extensively in many research programs to explore enhanced capabilities in aeronautical and space applications. The use of smart materials such as shape memory alloys gives us the chance to design mechanical and aerospace structures for better system performance, such as low vibration, shape control, and structural health monitoring. Such technologies, transitioning rapidly from basic research to reliable applications with a certain profile of maturity, offer the possibility of expanding current structural functionalities or replacing existing ones in retrofit applications. © 2015 Elsevier Ltd. All rights reserved
Flutter di Velivoli con comandi Fly By Wire e Non Linearità
No full textScopo di questa tesi è lo sviluppo di metodologie affidabili per l’esecuzione di analisi di flutter non lineare, applicabili a velivoli con comandi manuali e a velivoli con comandi Fly By Wire.
Lo sforzo è mirato all’arricchimento del pacchetto, già a disposizione, di codici in house per l’analisi di flutter, mantenendone invariato l’approccio, che è quello che utilizza la tecnica della sottostrutturazione dinamica (extra modi). Tale approccio sarà esposto in dettaglio nel Capitolo 2 e rappresenta la costante di tutto ciò che sarà prodotto per il flutter non lineare, [1].
La ragione della scelta degli argomenti della tesi risiede nella necessità, ravvisata dal mondo industriale, di strumenti affidabili e veloci, che consentano di rispondere alle esigenze certificative sia di velivoli di piccole dimensioni che di velivoli di grandi dimensioni.
Il cuore della tesi è costituito da tre capitoli (Capitolo 2, Capitolo 3, Capitolo 4), con livello incrementale di problematiche da affrontare.
Nel Capitolo 2 si metterà a punto la tecnica del bilancio armonico per effettuare analisi di flutter nel dominio della frequenza per un velivolo di categoria EASA CS 23, in presenza di non linearità nel movimento d’alettone.
Nel Capitolo 3 si scriveranno le equazioni del sistema aeroelastico in presenza di leggi di controllo o comandi servopotenziati, nell’ipotesi di linearità del sistema. Il metodo sarà applicato su due casi molto diversi tra loro: un velivolo sperimentale non convenzionale, nel quale sarà considerata la legge di controllo dell’elevatore (flutter a ciclo chiuso) e un velivolo di categoria business jet (EASA CS 25), nel quale sarà considerata la presenza del servoattuatore idraulico dell’elevatore, le cui equazioni sono esposte in APPENDICE A, [2].
Nel Capitolo 4 si utilizzerà l’approccio precedente (Cap. 2), introducendo però le equazioni non lineari della dinamica del servoattuatore idraulico, pervenendo quindi alla scrittura delle equazioni del flutter non lineare, che saranno risolte con integrazione nel tempo.
Le analisi di flutter di routine sono condotte con l’ipotesi di linearità: gli spostamenti sono piccoli, le forze aerodinamiche sono proporzionali alla risposta e gli elementi del sistema di controllo rispondono linearmente con l’ampiezza dello spostamento. È noto tuttavia che nei sistemi reali sono presenti fenomeni non lineari sia dal punto di vista strutturale che dal punto di vista aerodinamico. Tali non linearità influenzano il comportamento aeroelastico del velivolo e le metodologie lineari non sono in grado di prevederlo con accuratezza.
Le sorgenti di non linearità possono risiedere:
nella struttura, ad esempio la rigidezza cubica degli attacchi dei motori, il gioco nelle superfici mobili, le rigidezze bilineari dovute alla presenza di spring tab o le non linearità distribuite dovute ai giunti meccanici,
nell’aerodinamica, ad esempio nel regime transonico, in cui la posizione dell’onda d’urto dipende dalla risposta dell’ala, quindi vi è una relazione non lineare tra il movimento della struttura e le forze aerodinamiche su di essa agenti
Effectiveness of Wing Twist Morphing in Roll Control
No full textThis paper is focused on numerical investigations that analyze the advantages obtained from high-aspect-ratio wings with unconventional roll control strategies based on wing twist morphing. A sailplane, the G103-B, produced by the GROB Werke company, was chosen as the reference aircraft for the analyses. For confidentiality reasons, the data disclosed by the builder covered only general properties such as the main dimensions, the lifting surface airfoils and attitudes, the characteristic speeds and a rough mass budget. As a consequence of this, “reverse-engineering” was considered necessary to define a reasonable wing structural layout that enabled the analysis of the elastic-aircraft roll dynamics. A preliminary sizing of the wing structure was addressed using CS-22 airworthiness requirements and by adopting fast, elementary approaches that are well known in the literature. The estimated structural arrangement, which was verified using a finite element analysis, was then used to generate the aircraft dynamic model. The elastic-aircraft roll dynamics were first investigated with regard to conventional aileron-based control. Extra modes simulating controlled twist distributions along the wing span were added into the aircraft modal base and their effects on the aircraft roll dynamics were analyzed. The conventional (aileron-based) and the unconventional (wing twist morphing) roll control strategies were compared from the aerodynamic and the aeroelastic standpoints, and the benefits achieved with the unconventional strategy are summarized
Aero-servo-elastic design of a morphing wing trailing edge system for enhanced cruise performance
No full textThe Adaptive Trailing Edge Device (ATED) was a sub-project inside SARISTU (Smart Intelligent Aircraft Structures, 2011–2015), an L2 level project of the 7th EU Framework programme coordinated by Airbus, aimed at developing technologies for realizing a morphing wing for the improvement of general aircraft performance. That study, divided into design, manufacturing and testing phases, involved universities, research centers and leading industries of the European consortium. The aim of the present work is to predict the aero-servo-elastic impact of a full-scale morphing wing trailing edge on a CS-25 category aircraft. Within SARISTU, many FE models were realized, taking into account the complete and complex adaptive wing structure behavior. Those numerical representations referred to the 5.5 m wing section that was then employed for wind tunnel tests; such segment included the winglet and was representative of the outer wing segment (namely, the so-called “aileron region”). Those models were taken as reference to develop numerical representation of the considered wing that better suited the complete wing segment, from the fuselage attachment to the end of the flap region. Therefore, a scaling process was necessary, aimed at translating the former architectures to the new geometries. This kind of extrapolation had the advantage to take into account larger rooms to host the complex actuator system with all its components. MSC Nastran® FE models were elaborated to estimate stiffness and inertial distributions that allowed constructing the stick-beam mock-up of the complete structure. Several cases of flutter analysis were investigated by an in-house code, SANDY 3.0, to verify the safety requirements imposed by the applicable aviation regulations (paragraph 25.629, parts a and b-1). Moreover, dynamic stability assessment was performed with respect to single and combined failures of the actuation line and kinematic chain enabling morphing in order to support FHA (Fault and Hazard Analysis)
SARISTU - Smart Intelligent Aircraft Structures
No full textSARISTU (Smart Intelligent Aircraft Structures) focuses on the cost reduction of air travel through a variety of individual applications as well as their combination. For the first time ever in smart material concepts, SARISTU offers the opportunity to virtually and physically assess the interaction of different technological solutions and their combined effects at aircraft level.
Specifically, the joint integration of different conformal morphing concepts in a laminar wing is intended to improve aircraft performance through a 6% drag reduction, with a positive effect on fuel consumption and required take-off fuel load. A side effect will be a decrease of up to 6dB(A) of the airframe generated noise, thus reducing the impact of air traffic noise in the vicinity of airports.
Another important objective is to limit the integration cost of Structural Health Monitoring (SHM) systems by moving the system integration as far forward in the manufacturing chain as possible. In this manner, SHM integration becomes a feasible concept to enable in-service inspection cost reductions of up to 1%.
Finally, the incorporation of Carbon Nanotubes into aeronautical resins is expected to enable weight savings of up to 3% when compared to the unmodified skin/stringer/frame system, while a combination of technologies is expected to decrease Electrical Structure Network installation costs by up to 15%
A SMA-based morphing flap: conceptual and advanced design
No full textIn the work at hand, the development of a morphing flap, actuated through shape memory alloy load bearing elements, is described. Moving from aerodynamic specifications, prescribing the morphed shape enhancing the aerodynamic efficiency of the flap, a suitable actuation architecture was identified, able to affect the curvature. Each rib of the flap was split into three elastic elements, namely "cells", connected each others in serial way and providing the bending stiffness to the structure. The edges of each cell are linked to SMA elements, whose contraction induces rotation onto the cell itself with an increase of the local curvature of the flap airfoil. The cells are made of two metallic plates crossing each others to form a characteristic "X" configuration; a good flexibility and an acceptable stress concentration level was obtained non connecting the plates onto the crossing zone. After identifying the main design parameters of the structure (i.e. plates relative angle, thickness and depth, SMA length, cross section and connections to the cell) an optimization was performed, with the scope of enhancing the achievable rotation of the cell, its ability in absorbing the external aerodynamic loads and, at the same time, containing the stress level and the weight. The conceptual scheme of the architecture was then reinterpreted in view of a practical realization of the prototype. Implementation issues (SMA - cells connection and cells relative rotation to compensate the impressed inflection assuring the SMA pre-load) were considered. Through a detailed FE model the prototype morphing performance were investigated in presence of the most severe load condition
- …
