A Working Group consisting of NLR, QinetiQ and ONERA constructed the ASTERA taxonomy for aeronautical R&T. This is a hierarchical taxonomy that builds upon existing European structuring efforts, such as the GARTEUR taxonomy and EUROCONTROL's ARDEP taxonomy.
The ASTERA taxonomy has been defined, reviewed and agreed upon by a considerable group of experts from different fields within the European aeronautics community. This has given the taxonomy a strong foundation. Therefore EASN uses and if necessary modifies this taxonomy in order to approach a classification of university activities in the field of aeronautics.
Metallic Materials & basic processes
High temperature materials for engines and light alloys for airframe. Improvement of the properties of already in use materials, improvement of materials in the process of being introduced, prospection and development of new materials. Development of new assembling technologies and the corresponding modelling (link with 204 and 205). Development of specific tools for materials processing (alloy making furnaces, powder metallurgy, deposition techniques, oxidation and corrosion furnaces, heat treatments furnaces, machining facilities). Techniques of physico-chemical and microstuctural investigations (Xray analysis, scanning electron microscopy and microanalyses). Mechanical characterisation.
2. Aluminium alloys.
3. Titanium aluminides.
4. New weldable alloys.
6. Oxidation, corrosion.
7. Assembling processes.
8. Repairing processes.
9. Microscopical analyses.
10. Chemical analyses.
11. Mechanical testing.
Non-Metallic Materials & basic processes
Organic and ceramic materials in different forms (film, monolith, fibre). Surface protection (oxidation, corrosion, thermal barrier), ceramics for structural and electrical engineering (blades and hot parts of engines, electromagnetic windows, ball bearing, electric insulators, fibres and nanotubes), processing routes (PVD, CVD, sintering, reaction-bonding, directional solidification, cold and hot isostatic pressing, melting and spinning, laser ablation and electric discharge).
1. Carbide and nitride of silicon.
2. Organometallic precursors of ceramics (alkoxides and organosilicon polymers).
3. Organic precursors of carbon (PAN, pitch).
4. Glass and glass-ceramics.
7. metallic sulphides and fluorides.
9. aramid, glass.
10. carbon and boron nitride nanotubes.
11. thermal barrier coatings.
Composite Materials & basic processes
Life prediction (residual stress, damage propagation, oxidation and corrosion) and multi-scale modelling taking into account the fibre/matrix interface. Development of micromechanical characterisation tools (instrumented microindentation at room and high temperature, push-out and push-in). Ceramic Matrix Composites (CMC) : hot parts for turbine engine (nozzle flaps, thrust vectoring nozzles, flame-holder, exhaust cones), rocket propulsion (thrust chambers, exit nozzles and nozzle throats) and thermal protections. Composites reinforced with long fibres or fillers. Processing routes (sintering, hot pressing, reaction bonding, liquid infiltration, chemical vapour infiltration). Organic Matrix Composites (OMC) : main body and wings for both subsonic or hypersonic aeroplanes and helicopters, outer ducts for engines, tanks, structural components for satellites and rockets, thermal protections. Short or long fibre composites, compounds (premix or nanotubes). Processing routes (press moulding, autoclave, RTM, filament winding, tow placement). Metal matrix composites (MMC) : aero-engines hot parts (compressor disks, drive shafts, blades) and structural components (aircraft landing gear, rocket motor casing, missile fins, satellite antennas). Continuous fibre-reinforced and particulate-reinforced composites. Processing routes (liquid infiltration under moderate pressure, fibre coating and HIPing, powder metallurgy).
1. CMC: matrices (carbide and nitride of silicon, glass-ceramics, carbon) ; fibres (silicon carbide, carbon, oxide) and fillers (silicon carbide).
2. OMC: matrices (thermosetting resins, thermoplastic polymers, thermostables and elastomers); reinforcement by fibres (carbon, polyethylene, polyaramide, glass, plant fibres) and by particles (mineral, nanotubes).
3. MMC: matrices (conventional titanium alloys, titanium aluminides, nickel-based superalloys, aluminium and magnesium alloys); fibres (silicon carbide, alumina, carbon) and particles (carbides).
4. Elaboration processes.
5. repairing processes.
Advanced Manufacturing Processes & Technologies
Advanced Manufacturing Engineering processes involve the design, production engineering and transition to factory operation of competitive manufacturing processes, techniques, methods and tools.
1. Flexible Manufacturing.
3. composite components.
4. fibre-metal laminates.
5. Ribbon Organised Wiring.
6. High speed machining: metal parts.
7. Fabrication simulation: all kind of manufacturing processes to reduce start up time.
8. Welding technologies.
8.1. Friction stir welding : metal structures.
8.2. Laser beam welding: metal structures.
9. Explosive forming.
10. Advanced castings.
11. Super plastic forming: metal structures, in particular titanium.
12. Resin transfer moulding: composite structures.
13. Tau placement: automated fibre placement, composite structures.
14. Thermo-plastics: composite structures.
15. Riveted Joint.
16. Bonded Joint.
17. Conformal antennas.
Structural Analysis and Design
Structural analysis and design consist in all the steps necessary to guarantee that any structural part will be able to fulfil its requirements. It encompasses the conception and design (with links with CAD) and the prediction/verification of strength to static loads (stress analysis) and low amplitude cycling loads (fatigue). The effects of the environment (such as ageing, thermal loads, moisture effects, . . .) are included in this domain.
1. Metallic Material constitutive laws (linear elasticity, plasticity, viscolelasticity).
2. Composite laws (linear and non-linear domains).
3. Numerical methods (finite element, solving methods).
4. Composite and multilayer structure modelling.
5. Static Stress analysis with damage and failure criteria.
6. Fatigue behaviour analysis with crack initiation and propagation.
7. Multi-scale modelling methods for CMC, OMC and MMC materials.
8. Buckling (linear and non-linear approaches) for metallic components.
9. Buckling for composite structures with or without stiffener.
10. Post-buckling (crack initiation and delamination propagation).
11. Assembling modelling (rivets, bonding, FSW techniques,..).
12. Optimisation methods.
Study of flexible structures situated in a flowing fluid. The origins are in the field of aerospace engineering (aeroplanes, helicopters rotors, turbomachineries, launchers and missiles), but aeroelasticity concerns also civil engineering (bridges, towers), mechanical and nuclear engineering. The first objective of aeroelasticity is to guarantee the integrity of the structure in the flow. Aeroelasticity is the study of the mechanics of coupled aerodynamics-structure systems: the structure is taken in the usual mechanical sense of the term, which is to say that it includes the passive structure and the structured coupled to control systems (flight controls, control law). In fact, the term aero-servo-elasticity is often used. High temperature environments can be important in aeroelastic problems, hence the terms aero-thermo-elasticity. So aeroelasticity incorporates the theory of continuum mechanics, fluid mechanics, and automatic systems. The scientific fields concerned, then, are steady and unsteady aerodynamics, the static and dynamic structure with its linear or non-linear properties, the servo controls, also with their linear and non-linear properties, and the coupling loop between the aerodynamics, the structure, and the systems. Aeroelastics problems can be static and dynamic: In dynamic aeroelasticity, there is a further subdivision of problems into two broad types. The first type is when the flow is unsteady and the structure is in a steady position, but behaves dynamically. This is the case of problems having to do with atmospheric turbulence, boundary layer separation, and shock wave-boundary layer interaction. Buffeting also enters into this category of problems. The second type of general aeroelasticity problem has to do with those aeroelastic instabilities where the motion of the structure causes the forces, in that the aerodynamic forces do not exist without this motion. Flutter falls into this category and is the most important topic of aeroelasticity.
1. Static aeroelasticity: Linear and non linear structure, Steady aerodynamic, Static deformation, Static divergence, Aeroelastic optimisation.
2. Dynamic aeroelasticity: Structural dynamic (linear and non linear), Unsteady aerodynamic (linear and non linear), Fluid structure coupling, Fluid structure systems coupling, Flutter, Forced response.
3. Numerical aeroelasticity: Unsteady aerodynamic, Stability and response prediction, Aeroelastic optimisation, (multidisciplinary optimisation), Aeroelastic model updating, Aero-servo-elasticity.
4. Experimental aeroelasticity: Unsteady aerodynamic, Flutter model (design, manufacture, ground testing, wind tunnel testing).
5. Aeroelastic Certification: Ground vibration test, Flutter flight test.
Buckling, Vibrations and Acoustics
Activity on buckling consists of the development, improvement and validation of experimental and numerical methods for the prediction of buckling phenomenon and optimisation of structural components (metallic and composite materials) in aerospace domain. Vibrations and Vibro-Acoustics: Objectives of the structural dynamic are to determine the dynamic behaviour of structural systems excited by external or internal forces (mechanical, aerodynamics or acoustic) in order to guarantee the integrity of the structure in the environment and the comfort of the users. The objectives of the vibro-acoustics are the same for a structure coupled with a fluid. Two types of problems can be consider. The first type concerns the internal noise generated by vibrating structures. The second type concerns the acoustic discretion where the external noise is generated by vibrating structure. The studies concern the physical understanding of the mechanic and acoustic phenomena?s, their description, their quantification with theoretical, numerical and experimental means.
1 - Structural dynamics:
1.1. Structural dynamic modelling: Material modelling (viscoelastic media, composites, multilayer structure); Numerical method( (Analytical, Finite Element analysis), Statistic Energy Analysis); Linear and non linear analysis; Damping modelling; Structure internal fluid interaction (sloshing).
1.2. Multibody dynamics modelling: Kinematics and dynamics of rigid and flexible components.
1.3. Stress Waves in Solids: Waves propagation.
1.4. Structural Model updating 1.4. Dynamic Structural optimisation.
1.5. Shocks and vibrations: Transient response, Low frequency range, Medium and high frequency ranges.
1.6. Random Vibrations in Structural Mechanics: Linear and non-linear systems, Random excitation (turbulence, noise, acoustic).
1.7. Experimental Methods in Vibrations: Vibration properties of materials, Vibration technique in non-destructive testing, Systems excitations, transducers, Data acquisition, Signal processing and analysis,
1.8- Experimental Modal Analysis, FRF measurements.
2 - Elasto-acoustic:
2.1. Material properties: Homogeneous material, composites, viscoelastic media, multilayer, etc.; Acoustic material.
2.2. Modelling: Analytical approaches, Finite element analysis, Boundary Element analysis, Statistic Energy Analysis.
2.3. Sound Structure Interaction: Acoustic propagation, Acoustic radiation, Acoustic transmission through structures, Acoustic reflection from elastics structures, Acoustic excitation, Acoustic fatigue, Structure and fluid damping.
2.4. Experimental Identification.
Smart Materials and Structures
This domain consists in to equip structures with sensors, actuators and intelligence in order to give them some autonomy, adaptation capabilities or reduce the operational costs or nuisances (noise ...). The sensors provide the knowledge of the internal state and of the external environment. The actuators give the ability to adapt to internal and external changes. The intelligence permits the autonomous capacity to decide the optimal way of adaptation.
1. Miniaturisation of sensors (piezoelectric devices, optical fibers,..).
2. Integration of sensors.
3. Active Piezoelectric materials.
4. Electrostrictive materials.
5. Single crystals.
6. Magnetostrictive materials.
8. Shape memory alloys.
11. Control strategies.
12. Multi-functional materials.
13. Health Monitoring System.
14. Control of vibration.
15. Shape Control.
16. Active flow Control.
17. UAV, mini UAV.
Structures behaviour and Material Testing
Development and use of test facilities in order to get inputs for prediction tools (material properties characterisation of metallic and composite materials), validate prediction tools (determination of local or/global information such as strain, stress, plasticity, cracks, delamination phenomenon, . .) and to verify the behaviour of sub-components or real structure (limit strength, fatigue behaviour, . .).
1. Constitutive laws (metallic and composite materials).
2. Experimental static component behaviour.
3. Non-linear characterisation with and without temperature environment.
4. Buckling testing
5. Diffusitivity measurements (thermal properties. NDT).
6. Electrical and electromagnetic properties measurements (NDT).
7. Optical properties (NDT).
8. X Ray radiography (NDI).
9. Ultrasounds with and without contact (Air coupled or laser).
10. Eddy Current (NDI).
11. Thermography method (NDI).
12. Optical techniques (holography, shearography, Moire).
Internal Noise prediction
Activity on internal noise prediction consists of the development, improvement and validation of experimental and numerical methods for the prediction and the reduction of internal noise (aeroplane, helicopter, and launcher). This activity is a part of the Vibration and Vibroacoustic domain. To solve an Internal Noise Problem, we need the knowledge of the excitation sources, the dynamic behaviour of the structure, the propagation way of the vibration in the structure and in the internal fluid.
1. Material properties: Homogeneous material, heterogeneous structure, Composite material, viscoelastic media, multilayer, etc., Acoustic material, porous material, Material optimisation.
2. Modelling: Analytical approaches, Finite element analysis, Boundary Element Analysis, Statistic Energy Analysis, Energy diffusion;
3. Excitation sources: mechanic, aerodynamic, acoustic; Acoustic propagation, Acoustic radiation, Acoustic transmission through structures, Acoustic reflection from elastics structures.
4. Experimental Identification.
Helicopter aeroacoustics consists in:
- studying and identifying the aerodynamic phenomena causing noise generation and influencing noise radiation. The occurrence of these phenomena and their relative contributions to noise, strongly depend on flight conditions (take-off, descent, level flight at low, medium and high speed) and on the type of helicopter.
- Developing and validating computational tools for prediction of helicopter noise with the following objectives:
- quantification of helicopter nuisance,
- quiet helicopter design (rotor, turboshaft air intake and acoustic lining),
- determination of low noise flight procedures (for civil applications)
- determination of low detectability manoeuvres and flight procedures (for military purposes). Helicopter noise sources comprise main and tail rotors and turboshaft engines. Research activities consist in:
- physical modelling and numerical simulations,
- wind tunnel or static tests and helicopter flight tests.
Key issues for an accurate numerical prediction of helicopter noise are:
- for rotor noise, a precise prediction of the main rotor wake and vortices which may interact with main rotor and even tail rotor blades, depending on flight conditions.
- for turboshaft engine noise, a precise prediction of acoustic propagation in the complex flow and geometry of the engine air intake.
1. Sub-domains according to the origin of the sources:
1.1. main rotor noise.
1.2. tail rotor noise.
1.3. turboshaft engine noise.
2. Sub-domains according to the nature of noise:
2.1. discrete frequency noise related to periodic aerodynamic phenomena The nuisance from helicopter rotors is very much increased when a certain type of discrete frequency noise called "helicopter rotor impulsive noise" occurs. This "impulsive noise" includes Blade Vortex Interaction (BVI) noise in descent and low-to-medium level flight and High Speed Impulsive noise (HSI).
2.2. broadband noise, mainly due to interactions between rotating components (rotor and compressor blades) with incoming turbulence.
1. Internal noise reduction. Active Control. The aim is to decrease the level of noise due to the vibrations of structures with the use of active control algorithms able to take into account different noise sources, i.e. wide band excitations.
2. External noise reductionReduction at the source; acoustic absorbing materials (passive and adaptive).Link with ATM and Human Factors (noise perception).
1. Active Control algorithms.
2. Techniques in relation with actuators and sensors such as piezoelectric or piezoceramic materials, electrostrictive ceramics? and their mechanical modelisation (link with 208).
3. Automatics and real time systems for the study and for the realisation of controllers.
4. Optimisation of the location of patches on the structures.
5. Modal identification of structures.
6. Knowledge of noise sources and identification of acoustic leaks.
7. Acoustic measurements for the validation of Active Control.
8.1. Optimisation of aerodynamic and acoustic performance through new design of fan blade and vanes, advanced propellers (possibly uneven spaced), and helicopter rotors.
8.2. Novel aircraft designs to mask some sources, or to alleviate installation effects (interactions) on noise generation.
9. Acoustic linings:
9.1. New concepts of passive or adaptive materials.
9.2. Extensions to high temperatures on the exhaust duct.
10. Noise abatement procedures.
Acoustic Measurements and Test Technology
Acoustic measurements deal with pressure field using microphones and pressure transducers, in association if needed with other probes, as accelerometers or DLV. It constitutes the basis for experimental studies concerning noise pollution, noise reduction, acoustic detection and ranging, and acoustic fatigue. Depending of the application, attention is focused on the radiated far-field (vehicle certification), the near acoustic field (cabin noise, vibro-acoustics), the characterisation of noise sources (physical phenomena responsible for vehicle noise emission such as turbomachinery noise, jet noise, airframe noise, installation effects), the acoustic imaging (detection and ranging). Measurements are made at model scale (anecho?c room, wind-tunnels) or at full scale. Acoustic measurements are strongly coupled with signal processing, in particular concerning localisation and active noise control. They are also strongly interested in psychoacoustics and the definition of noise annoyance indicators.
1. Sensors and transducers: condenser microphone, loudspeakers, acoustic driver, accelerometer, sound intensity probe, smart transducer, pistonphone, DLV.
2. Units: physical units (Pa, dB), psychoacoustical units (dBA,PNdB, EPNdB, Leq,?).
3. Common measurements: calibration, absorption, convection, refraction, reverberation, near-field and far-field, intensimetry.
4. Machinery and airframe noise measurements: anecho?c room, reverberation chamber, wind tunnel, flight tests, internal and external noise.
5. Noise source localisation and ranging: microphone array, acoustic mirror.
6. Acoustic signal recording and processing: narrow band frequency analysis, third octave and octave bands, correlations, random noise, impulsive noise.
7. Certification procedures.
8. Acoustic detection.
9. Active noise control.
Aircraft security measures are the physical protection measures required in order to protect the aircraft and the passengers and crew when they are on-board.
1. Flight deck barrier devices (e.g. impenetrable cockpit doors).
2. Bomb-proof cargo containers (to contain effects of explosions).
Comment: see also Area 'AIRCRAFT AVIONICS SYSTEMS & EQUIPMENT'.