crashworthiness of fuselage hybrid structure 8iarcsfc 2016 k · crashworthiness of fuselage hybrid...

Crashworthiness of fuselage hybrid

structure

October 24-27, 2016

8IARCSFC 2016 – ATLANTIC CITY

D. HACHENBERG / V.LAVIGNE / M.MAHE

EIGHTH TRIENNIAL INTERNATIONAL AIRCRAFT FIRE AND CABIN SAFETY RESEARCH CONFERENCE

© AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document.

Contents

Page 2

Application of dynamic simulation on the aircraft

Hybrid fuselage crashworthiness technical challenges

Crashworthiness building block approach

Dynamic numerical analysis as Means Of Compliance

Synthesis

3

4

5

2

1

October 24-27, 2016EIGHTH TRIENNIAL INTERNATIONAL AIRCRAFT FIRE AND CABIN SAFETY RESEARCH CONFERENCE



More than 20 years of experience for both metallic and composite airframe structures

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Bird strike(inlet)

Bird strike(cockpit)

Tyre debris impact(LGB area)Fan Blade Off

(Nacelles)

Bird strike(wing LE)

Bird strike(VTP/HTP)

• Impacts: bird strike, tyre debris, rim debris, Hard Debris Impact, military threats, hail impact

Crash (Fuselage)

• Crash and ditching




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Extensive usage of dynamic analysis from early development stage:Close collaboration between material, design, stress and test up to process and manufacturing

Design principles: investigate technologies, concept

Detailed sizing : safe and optimised design

Experimental tests : define optimal test set-up and de-risk tests

Compliance demonstration

� Bring robustness to the design



Fuselage crashworthiness requirement

• Regulation: (CS/FAR 25.561): “The structure must be designed to give each occupant every reasonable chance of escaping serious injury in a minor crash landing”

• EASA & FAA raised a Special Condition (SC) on crashworthiness to address new fuselage concept (CFRP material):

• For fuselage crashworthiness, the SC requires the demonstration of Equivalent Level Of Crash Survivability w.r.t. already certified comparable metallic aircrafts. Comparison is addressed based on 4 survivability criteria :

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- Living space- Retention of heavy items of mass- Passenger acceleration levels- Maintenance of egress path




Find the right balance between : • Ensure the maintenance of the living space.

[ENABLER]: limit the deformation of cabin floor & c abin upper structures

• Limit the passenger acceleration levels = limited & regular deceleration during impact.[ENABLER]: mechanism of energy absorption : intrins ic structure behaviour w/o additional features

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Passenger accelerationStructure deformation

Living spaceStructure integrity

1.




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� Need for predictive, reasonably quick numerical tool to be used all along the aircraft development

2 frame bay DFEM

3. Complex analysis • Large fuselage section DFEM• Crash duration ~500 ms• High deformation and multiple failures involved• Several pax/cargo load configurations

2. Hybrid structure: coexistence of two material behaviours:• Metallic ductile (plastic deformation)• Composite primarily elastic behaviour but good design can offer

efficient energy absorption




Page 8

Test Pyramid Analysis PyramidFull

Analysis PyramidTruncated

Test Pyramid

Material failure models

Elementary failureKey level to build confidence in analysis

Sequence of crash eventsEnergy absorption

Deformation and failure mode




• Added value of pre-test simulation:• Define appropriate test set-up and conditions (tolerances …)

• Define instrumentation means and set-up : HS camera, strain gages, displacement sensors, load cells

• De-risk test: robustness analyses including test condition tolerances, back-up instrumentation.

� Right the first time

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[identification] Material and joints full characterisation up to failure

� Extensive test programs = key to set up accurate failure models allowing to build confidencePage 10

Coupon level

Fibre failure

Matrix failure

Shear failure

Composite material:Intra & inter-laminar properties

- Elastic properties- Strengths- Shear damage/plasticity- Fracture toughness

DCB …

Joints: metallic, composite, hybrid

Bolt Pull-Through Test (BPT)

Single (Double) Lap Shear Test

- Elasto-plastic inc. failure for tensile, BPT, shear

Metallic material:Tensile/compressive properties

- Elastic properties- Hardening- Damage & plastic failure




[validation] Understanding & prediction of elementary failure of parts or function

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� Good level of prediction of the deformation and failure modes under crash loading

Element /Detail level

Under static loading- Metallic frame bending- Composite frame bending…Under dynamic loading- Clip failure- Composite strut- Metallic strut…

T=2 ms T=2 msFalling mass on an “upside-down” specimen �Unfolding/bending failure

CLI

P

Falling mass on an “upside-down” specimen �compressive/bending failure

ST

RU

T




[validation] Prediction of crash mechanisms sequence and structural failure modes

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Sub-component level

Under crash loading- Frame assembly

Falling mass on an “upside-down” specimen

3 frames curved panel specimen

Correlation of :- clip failure- frame deformation- skin bending

� Good level of prediction of crash mechanisms, sequence of events, energy absorption capability� Sequence of events & energy absorption

�Elementary failure mode




[validation] Prediction of crash mechanisms sequence and structural failure modes

Sub-component level

Under dynamic loading

- Fuselage bilge structure

Correlation of :- clip/strut failure- frame deformation- skin bending

� Good level of prediction of crash mechanisms, sequence of events, energy absorption capability

Falling mass on an “upside-down” specimen

Fuselage bilge area (multi frames)

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A350XWB

AN

ALY

SIS

(MoC

)

A340

Dynamic numerical analysis as Means of Compliance

Page 14

A320

TE

ST

AN

ALY

SIS

(CO

RR

ELA

TIO

N)

CEAT - 1995

Truncated test

pyramid

correlation

EQUIVALENCEIn several pax/cargo loading conditions

CERTIFICATION

Material& Joints

Frameassembly

Frames

CFRPBilge struts

Sub cargo floor

Clips

Material& Joints

Frameassembly

Frames

CFRPBilge struts

Sub cargo floor

Clips

A350XWB MoC= Analysis

supported by tests

validation



Synthesis

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Maturity of dynamic simulations for both metallic and composite structures

Future need of intensive usage of validated dynamic simulation to select: material, technologies and design principles

High level of robustness of the developed hybrid fuselage concept versus crashworthiness requirement

Further usage of validated dynamic simulations for derivative and future programs


Build model for dynamic numerical analysis, validation, test program, run simulations, and analysis of results = significant engineering effort


November 2015AEROSPACE STRUCTURAL IMPACT DYNAMICS INTERNATIONAL CONFERENCE

© AIRBUS Operations S.A.S. All rights reserved. Confidential and proprietary document. This document and all information contained herein is the sole property of AIRBUS Operations S.A.S. No intellectual property rights are granted by the delivery of this document or the disclosure of its content. This document shall not be reproduced or disclosed to a third party without the express written consent of AIRBUS Operations S.A.S. This document and its content shall not be used for any purpose other than that for which it is supplied. The statements made herein do not constitute an offer. They are based on the mentioned assumptions and are expressed in good faith. Where the supporting grounds for these statements are not shown, AIRBUS Operations S.A.S. will be pleased to explain the basis thereof. AIRBUS, its logo, A300, A310, A318, A319, A320, A321, A330, A340, A350, A380, A400M are registered trademarks.

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crashworthiness of fuselage hybrid structure 8iarcsfc 2016 k · crashworthiness of fuselage hybrid...

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