eu fp6 vulcan industrial seminar, 23 feb 2011, spain … a-sener... · · 2012-09-27......

© SENER Grupo de Ingeniería, S.A. – Getxo, 2011

EU FP 6 VULCAN, Industrial Seminar, 23 Feb 2011

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EU FP6 VULCAN Industrial Seminar, 23 Feb 2011, Spain

Aircraft structure “hardening” by Design. Overview of Implict and explicit strategies for FIRE and BLAST

protection

Ben Park, Senior Aerospace Engineer



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• Implicit hardening (SENER and WUT)Modification of the aerostructure to prevent catastrophic failure.

• Explicit hardening (University of Patras)The use of hardened liners to cover floors and sidewalls to prevent catastrophic failure.

Aircraft structure “hardening” by Design. Overview of Implict and explicit strategies for

FIRE and BLAST protection



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Implicit Hardening for Blast LoadingPrevious experience indicates that improving the ‘damage tolerance’ of aircraft structure to blast is what is needed, (Lockerbie report conclusion of AAIB):“The final recommendation is that Airworthiness Authorities and aircraft manufacturers undertake a systematic study with a view to identifying measures that might mitigate the effects of explosive devices and improve the tolerance of the aircraft's structure and systems to explosive damage.”

Lockerbie catastrophic fuselage failure QANTAS QF0302000 psi oxygen bottle explosionLocal fuselage failure at altitude

VULCAN



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Implicit Hardening for Blast LoadingCurrent Code of Federal Regulations (CFR), part 25, § 25.795(c), “Least risk bomb location.” (LRBL) means of compliance per AC 25.795-6 published 24/10/08;

When determining the LRBL, the following operational and design issues should be addressed: (a) If the applicant chooses a site adjacent to the fuselage skin, the applicant should assume that a portion of the structure will be lost. The applicant should determine the structural capability of the airplane in the presence of the resulting opening.

According to FAA, following ATA calculation, the total weight increase due to this new regulation is estimated at 160 Kg (354 pounds) per aeroplane. This induces additional fuel consumption (19 000 litres per year per aeroplane), which is evaluated by FAA to be around 9 000 US Dollars per year per aeroplane.



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Aluminium airplane structure with bolted joints between skin, stringers and frame

Composite Airplane structure with stringers bonded to skin, and frame joined to skin by bolts.

Implicit Hardening for Blast Loading



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Implicit Hardening for Blast LoadingVULCAN Aircraft Structure Test Program



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A series of tests were performed on flat rectangular panels made of aluminium, Carbon fibre reinforced plastic (CFRP) composite and Glare. The panels were subject to blast from high explosive charge weights from X to 3X grams at 20 cm standoff from the panels as shown below. A description of the different panels tested is given in the table below.

Flat panel blast test rigMaterial Dimension (mm2) Thickness (mm)

Aluminium (2024-T3) 800X800 1.0

CFRP (T300-3KPW fabric/epoxy) 800X800 2.0 [45/0/90/0/45/]s

Glare 3-2/3 800X800 1.7 [0.4Al/0/90/0.4Al/90/0/0.4Al]

General specifications of flat panels




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PAMCRASH Explicit Finite Element Model of Flat PanelsShell elements were used to represent the plate, laminated composite plate material properties were represented using elastic and elastic-plastic MAT 106 property cards. An explicit simulation of the structures response to a time varying blast pressure wave was performed.

PAMCRASH Plate Model mesh

GLARE Fibre Metal Laminate


Pressure-time variation for a blast wave.



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Flat Panel Test vs Simulation ResultsThe numerical simulation of the behaviour of rectangular panels made of 2024-T3 1.0 mm thick Aluminium, showed good agreement with test panel behaviour.

PAMCRASH aluminium plate simulation (X g C4)

Deformed Aluminium Test panel (X g C4)




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Failed Aluminium Test panel 2X g C4PAMCRASH Aluminium plate failure simulation

Flat Panel Test vs Simulation ResultsThe numerical simulation of the failure of rectangular panels made of 1 mm thick 2024-T3 Aluminium, showed good agreement with test panel behaviour.




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Failed CFRP Test panel X g C4 PAMCRASH CFRP plate failure simulation

Flat Panel Test vs PAMCRASH Simulation ResultsThe numerical simulations of rectangular panels made of 2mm thick T300-3KPW carbon fabric/epoxy (CFRP), showed good agreement with test panel behaviour.




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GLARE Test panel 3X g C4 PAMCRASH GLARE simulation (3X g C4)

Flat Panel Test vs PAMCRASH Simulation ResultsThe numerical simulations of rectangular panels made of 1.7 mm thick GLARE, showed good agreement with test panel behaviour.


No GLARE panel failures observed up to 3X g C4 !



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A series of tests were performed on fuselage frame to skin joints with Titanium aerospace bolts. The frames and skin specimens were made of aluminium, CFRP (Carbon fibre reinforced plastic, composite) and an aluminium frame mounted to a Glare skin. The test pieces were were subject to dynamic tension loading using a shock table from TNO as shown below.

Small shock table for castellation testing Velocity: 6.5m/s, Displacement: 50mm

Aluminium Castellation Test Specimen



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Structure: 61114 Shell elements

Bolts: P-link

Bonded Joints: Tie elements

Implicit Hardening for Blast LoadingCastellation Pull Off Test PAMCRASH Finite Element ModelShell elements were used to represent the plate, metal and laminated composite plate material properties were represented using elastic and elastic-plastic MAT 106 property cards. An explicit simulation of the structures response to a time varying blast pressure wave was performed.

Boundary Conditions for Pull Off Test Specimen PAMCRASH model



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Implicit Hardening for Blast LoadingCastellation Test vs PAMCRASH Simulation ResultsThe numerical simulations of the castellation specimens made of 1.6 mm thick 2024-T3 Aluminium, showed good agreement with test specimen behaviour.

Failed AluminiumCastellation Test Specimen

(Dia. 4.8 mm EN6114 CountersunkTi Bolt pull thru skin)

PAMCRASH AluminiumCastellation simulation

(Dia. 4.8 mm EN6114 Countersunk Ti Bolt thru skin failure)



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Castellation Test vs PAMCRASH Simulation ResultsThe numerical simulations of the castellation specimens made of T300-3KPW carbon fabric/epoxy carbon fibre reinforced plastic (CFRP), showed good agreement with test.


Failed CFRP Castellation Test Specimen(Frame flange failure)

PAMCRASH CFRP Castellation simulation(Frame flange failure)

Skin; 2mm thick T300-3KPW fabric/epoxy Cleats; 2mm thick T300-3KPW fabric/epoxy Bolts; Dia. 4.8 mm EN6114 Ti countersunk bolts



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Implicit Hardening for Blast LoadingCastellation Test vs PAMCRASH Simulation ResultsThe numerical simulations of the castellation specimens made with 1.7 mm thick GLARE skin, showed good agreement with test specimen behaviour.

Failed GLARECastellation Test Specimen

(Dia. 4.8 mm EN6114 CountersunkTi Bolt pull thru GLARE skin)

PAMCRASH AluminiumCastellation simulation

(Dia. 4.8 mm EN6114 CountersunkTi bolt pull thru skin failure)



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Implicit Hardening for Blast LoadingCastellation Test vs PAMCRASH Simulation ResultsThe numerical simulation failure loads and displacements of the castellation specimens showed good agreement with test specimen behaviour.

MaterialTest Type Force to

failure [KN]

Displacement

[mm]

CFRP Experimental 6-7 4-5

Simulation 6.62 6.77

Aluminium Experimental 16-18 16-17

Simulation 10.1 15.8

GLARE Experimental 15-16 10-11

Simulation 13.3 20

Aluminium and GLARE castellations were 2 times stronger than the CFRP castellations !



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Implicitally Hardened FuselageDesign integrated into WP5 Test Barrels HAI Carbon/epoxy Fuselage Test Barrel


Test Barrel Diameter 1200 mm x 1300 mm long Material; T300-3KPW fabric/epoxy



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Hardened Fuselage Blast PAMCRASH SimulationCarbon/epoxy Barrell FE model


Frames;T300-3KPW fabric/epoxy Cleats; T300-3KPW fabric/epoxy Bolts; EN6114 Ti countersunk bolts

Skin; T300-3KPW fabric/epoxyStringers; T300-3KPW fabric/epoxy(Co-cured to skin)



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Implicitally Hardened FuselageDesign integrated into WP5 Test Barrels HAI Aluminium Fuselage Test Barrel


Test Barrel Diameter 1200 mm x 1300 mm long Material; Various aluminium alloys(Skin; 7178)



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Hardened Fuselage Blast PAMCRASH SimulationAluminium Barrell FE model


Skin; 7178-T762Stringers; 7075-T73511

Frames; 2024-T3Cleats; 7178-T762Bolts; EN6114 Ti countersunk bolts



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Hardened Fuselage Blast PAMCRASH Simulation

FE model blast pressure loading;

Carbon/epoxy Barrel, Model 9;Aluminium Barrel, Model 17;

Pr

0.28 Pr

0.2 Pr

0.28 Pr

Charge Standoff, R=20 cm

Barrel diameter=120 cm




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Hardened Fuselage Blast PAMCRASH SimulationAluminium Barrell Preliminary Results

Time: 1 ms, (Model 17) Time: 5 ms, (Model 17)




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Hardened Fuselage Blast PAMCRASH SimulationAluminum Barrell Failure (Model 17)




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Hardened Fuselage Blast PAMCRASH SimulationAluminum Barrell Failure (Model 17 sectioned view)




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Hardened Fuselage Blast PAMCRASH SimulationCarbon/epoxy Barrell Preliminary Results

Time: 0.5 ms, (Model 9) Time: 5 ms (Model 9)




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Hardened Fuselage Blast PAMCRASH SimulationCarbon/epoxy Barrel Failure (Model 9)




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Hardened Fuselage Blast PAMCRASH SimulationCarbon/epoxy Barrel Failure (Model 9 sectioned view)




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• Implicit Blast Hardening• Can be achieved by new materials such as GLARE.• Can be achieved by careful detail design of frame to skin joints,

specifically hardened cleats and skin padding.• Simulation tools are available now to analyse the problem to enable

hardened design to prevent catastrophic failure of aircraft from blast. • Further studies of hardening including a full scale fuselage blast

simulation will be given by WUT in the next presentation.

• FIRE hardening to be presented later by IVW & TECNALIA.

Thank You, Ben Park ([email protected])


CONCLUSIONS

eu fp6 vulcan industrial seminar, 23 feb 2011, spain … a-sener... · · 2012-09-27......

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