Overview
GRA 1: Low Weight Configuration (LWC) domain
The LWC domain focuses around the development of several technologies aimed at reducing the weight of aeronautic structures that meet the ‘green’ requirements of future regional aircraft. Most promising technologies have been selected through dedicated gates (Technologies Down Selections) at different levels of structural complexity from specimens up to full scale demonstrators (Figure 1).
Figure 1 – GRA ITD - LWC domain: project logic
The main technology streams investigated at the beginning of the Project were:
- Sensors for the detection of accidental damage, environmental effects and the consequent structural degradation during service.
- Multi-functional layers to improve and integrate in the composite structures the required additional functions (lightning or hail protection, etc.).
- Nanomaterials to reduce the weight of conventional composites by improving the mechanical characteristics obtained from the nanoparticles dispersed in the resin.
- Laser welding for integrated advanced metal alloy structures with a view to reducing weight through the removal of connecting devices.
Only technologies which passed the Second Down Selection were applied on full scale demonstrators: ground testing and, in particular, flight testing have been aimed at demonstrating the applicability of the technologies and solutions selected in this domain to future regional aircraft programmes.
Major Demonstrators
LWC domain Demonstrators
The final step of the technologies maturation road map is relevant to the technologies demonstration in a realistic experimental environment, representative of the operational conditions expected in flight (TRL 5/6).
The Full Scale Demonstrators identified in the LWC domain include (Figure 2):
- Fuselage Crown Stiffened Panel Demonstrator to be tested in flight
- Fuselage Barrel Demonstrator to be tested on ground
- Cockpit Demonstrator to be tested on ground
- Inner Wing Box Demonstrator be tested on ground
Figure 2 – LWC full scale demonstrators
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Fuselage Crown Panel In-flight Demonstrator
Participants
- Leonardo Aircraft Division (Italy)
- ATR (France/Italy)
- FHG (Germany)
- CIRA PLUS: CIRA (Coordinator – Italy)
- HAI (Greece)
Objectives
To demonstrate the composite reliability for Regional Aircraft during service and to obtain in-flight validation for the advanced technologies that require data acquired in an actual operating environment (TRL 6) through the following flight tests:
- flights with pristine Aluminium panel
- flights with Composite panel in undamaged configuration
- flights with Composite panel in damaged configuration
Features
The Composite Stiffened Fuselage Crown Panel (Length ≈ 4900 mm; Radius ≈ 1500 mm) has been installed on Section 13 of ATR72 MSN098 Test Aircraft (Figures 3, 4) and includes the following technologies:
- Advanced multi-functional composite material
- Damping Acoustic capability (including damping material, accelerometers and microphones)
- Structural Health Monitoring systems (including optical fibres, piezoelectric actuators/sensors, conventional strain gauges)
Figure 3 – ATR MSN098 before modification
Figure 4 – ATR MSN098 after modification
Tests
- Flights with pristine Aluminium panel to evaluate instrumentation functionalities and reference vibro-acoustic measurements – ATR – January 2015
- Flights with Composite panel in undamaged configuration to evaluate instrumentation functionalities, vibro-acoustic for data correlation and reference SHM measurements (Figure 5, 6) – ATR – July 2015
- Flights with Composite panel in damaged configuration (Figure 7, 8) to evaluate SHM measurements for data correlation – ATR – July 2015
Figure 5 – Flight test installation for Optical Fibres and Piezoelectric sensors/actuators measurements
Figure 6– Flight test installation for Acoustic evaluations
Figure 7 – Impact execution on Aircraft Figure 8 – Flight with Composite panel
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Fuselage Barrel Ground Demonstrator
Participants
- Leonardo Aircraft Division (Italy)
- HAI (Greece)
- FHG (Germany)
- Partner of Project AFLOG (under CfP): OMI (Italy)
Objectives
- To validate the advanced structural technologies applied at Full Scale Level on Fuselage Barrel including Pressure Bulkheads
- To demonstrate the achievement of TRL 6 through the following tests performed on the structure including artificial defects and damages due to impacts:
- Evaluation of Acoustic Transmission Loss (22-Loudspeakers Array around barrel & 20 microphones)
- Evaluation of the Damping Loss Factor (1-2 shakers & ~ 150 accelerometer positions)
- Pressurisation test (static & 90000 fatigue cycles)
Features
Full Scale Composite One Piece Fuselage Barrel (Diameter ≈ 3500 mm; Length ≈ 5000 mm) (Figures 9, 10, 11), reproducing the forward fuselage section of a regional aircraft (90 pax) including the following technologies:
- Pre-preg with damping layer for skin/stringers
- Thermoplastic for floor beams and windows frames
- Carbon fibre pre-preg curing out of autoclave for pressure bulkheads
- Fibre Optics – FOBG
- Fibre Optics – FOBR
- Piezoelectric sensors/actuators
- Wireless Sensors
Figure 9 – Composite One Piece Fuselage Barrel
Figure 10 – Fuselage thermoplastic floor grids Figure 11 – Fuselage thermoplastic window frames
Tests
- Acoustic Test – Leonardo Aircraft Division – May 2016 (Figure 12)
- Vibration Test – Leonardo Aircraft Division – June 2016
- Pressurisation Tests (Fatigue and Static) – Leonardo Aircraft Division – October 2016
Figure 12 – Composite One Piece Fuselage Barrel
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Cockpit Ground Demonstrator
Participants
- Airbus Defence & Space (Spain)
- Partners of several Projects (under CfP): PUMA, CRASHING, COMPASS, BME, HYBRIA, DIAAMOND.
Objectives
- To demonstrate an overall weight reduction in primary structure, improving functionalities of the reference metallic structure
- To validate the advanced structural technologies applied at Full Scale Level on Cockpit demonstrators
- To demonstrate the achievement of TRL 5 through
- vibro-acoustic tests
- static tests and fatigue tests including damage tolerance
- EMC test
Features
Full Scale Composite Cockpit (Figure 13, 14) realised in ‘One shot’ multifunctional co-cured stiffened skin including the following technologies:
- liquid resin infusion both for solid laminates and sandwich primary structure
- thermoplastic materials
- damping materials
- nanomaterial for electromagnetic protection
- SHM systems
Figure 13 – Cockpit (view forward) Figure 14 – Cockpit (view afterward)
Tests
- Vibro-acoustic test on MT1 – AIRBUS DS – July 2015 (Figure 15)
- Vibro-acoustic test on MT2 – AIRBUS DS – October 2015 (Figure 16)
- Static Test (UL) - AIRBUS DS – September 2016
- Damage tolerance - AIRBUS DS – October 2016
- EMC Test - AIRBUS DS – December 2016
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Inner Wing Box Ground Demonstrator
Participants
- AIRGREEN Cluster: Piaggio Aerospace (Coordinator – Italy)
- CIRA PLUS Cluster: CIRA (Coordinator – Italy)
- HAI (Greece)
- Leonardo Aircraft Division (Italy)
Objectives
To demonstrate the achievement of TRL 6 of SHM technologies applied at Full Scale Level on Inner Wing Box through the following tests performed on the structure, including artificial defects and damages due to impacts:
- Static tests
- Fatigue tests
Features
Full Scale Composite Wing Box (Composite Test Article Length ≈ 4500 mm; Max wing box Height ≈ 475 mm; Total Length including two dummies structures ≈ 13500 mm) (Figures 17, 18), reproducing the inner section of a wing of a regional aircraft (90 pax) including the following technologies:
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Piezoelectric sensors/actuators
Figure 17 – Composite Inner Wing Box Scheme Figure 18 – Preassembled Inner Wing Box
Tests
- Damage tolerance – Leonardo Aircraft Division – October 2016
- Static Tests (LL) – Leonardo Aircraft Division – October 2016
Fatigue and static tests will be performed intruding loads by 12 actuators connected to the metallic dummies (Figure 19).
Figure 19 – Inner Wing Box Demo, Structural dummies and actuators scheme