Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Fatigue resistance of wing
materials from the teardown of
AIRBUS A320 aircraft at the
end of life
Residual fatigue properties of a 2024-T351
aluminium alloy from the teardoawn of AIRBUS A320
wing panelsoafter service
Gilbert HENAFF 1
Fabien BILLY 1 – Guillaume BENOIT 1 – Sjoerd VAN-DER-VEEN 2
1
Pprime Institute
UPR CNRS 3346
Physics and Mechanics of Materials Departement
ISAE-ENSMA • Téléport 2
1 avenue Clément Ader • BP 40109
86961 FUTUROSCOPE - CHASSENEUIL Cedex, FRANCE
2 Airbus
Materials & Processes, ESW - Sub-domain
Research & Industrialisation, ESW1
D41, 18 rue Marius Tercé
31000 Toulouse, FRANCE
1
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Context of the study
~ 500 aircrafts dismantled between 2010 and 2013
6000 at 7000 commercial aircrafts will reach their age limit within
20 years
Evolution of regulations on management of the end of life
Industrial ecology
Aircraft Cemetery
Teardown
2
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
DIAGNOSTAT Project
• French National program sponsored by Interministerial
Fund (2008 – 2012)
• Endorsed by
competitiveness cluster
• Project leader :
– 4 industrial partners whose
– 6 public laboratories
3
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
DIAGNOSTAT Project
Development of innovative diagnostic tools on aircraft at the
end of life
– Securing market for spare parts
– Inspection without disassembly, improvement aircraft
maintenance
Development of a statistical tool to capitalize on knowledge
generated by the diagnostics of aircraft at the end of life,
characterizing the actual aging
– Validation of rules of aircraft design (enhanced security) and
redefinition of the end of life;
– Improving the future aircraft design,
4
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Pprime studies in DIAGNOSTAT project
Study parts and structures of aircrafts after teardown to have a
feedback on the aircraft structural health and to create a database of
defects.
Two topics addressed :
- Ageing of Carbon/Epoxy Composite (T300/914) materials from ATR72
and Falcon F10 aircrafts
- Residual fatigue strength of 2024-T351 aluminium alloy from wing
panels of an AIRBUS A320
5
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
AIRBUS A320 MSN004
First A320 to be dismantled in 2008 after:
•21 years of service
•38 617 flights (35342 hours)
6
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Objectives
AA2024-T351
Saturated solid solution
< 130ºC
GP zones
GPB zones
165ºC
Precipitation θ’’
Precipitation S’
200ºC
Precipitation θ’
Precipitation S
Al2CuMg
Precipitation θ
> 300ºC
Al2Cu
Metastable structure → Assesment of the impact of ageing on residual
fatigue properties ?
7
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Areas under investigation
Area close to the engine
and the pylon : higher
wing loading, higher
mechanical stress
forward
Area near wing tip : lower
wing loading, lower
mechanical stress
8
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Wing materials
Wing Length
2024-T351 laminated Aluminium alloy
L
TC
[1]
TL
% weight
(1) S precipitation: Al2CuMg
Cu
Mg
Mn
Fe
Si
Zn
Ti
Cr
3.8 – 4.9
1.2 – 1.8
0.3 – 0.9
< 0.5
< 0.5
< 0.25
< 0.15
< 0.1
(2) θ precipitation: Al2Cu
(3) Al-Cu-Mg-Mn-Fe-Si particles
(4) Al-Cu-Mn-Fe particles
(5) Matrix
[1]
C. Larignon, “Mécanismes d'endommagement par
corrosion et vieillissement microstructural d'éléments
de structure d'aéronef en alliage d'aluminium 2024T351,” PhD.,Université de Toulouse, 2011.
9
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Material characterization : Tensile tests
UTSpristine material < UTSwing tip < UTSarea close engine
YSpristine material < YSwing tip < YSarea close engine
10
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
65 mm
12 mm
Residual fatigue life
Mechanical polishing
1 µm
R = σmin / σmax = 0.1
th. 3 mm
20 Hz
Numbers of cycles to
failure
250 – 400 MPa
L and T directions
11
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Residual fatigue life
No significant difference
in residual fatigue
resistance
12
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Residual fatigue life
Differences in strength
noticed in tensile tests
Normalization by the yield
strength
No significant difference
13
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
SEM observations of the fracture
surfaces
Fracture
PropagationPropagation
Initiation
Fracture
Initiation
Secondary
initiation
Pristine, 250 MPa
Wing tip, 300 MPa
14
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
SEM observations of the fracture
surfaces
Pristine, 300 MPa
Wing tip, 250 MPa
Wing tip, 300 MPa
15
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
SEM observations of the fracture
surfaces
Presence of facets
Pristine, 300 MPa reminiscent of Stage I-like
propagation [2]
Local propagation along
{111} planes
No clear trend found …
Wing tip, 250 MPa
[2]
J. Petit, Some aspects of near-threshold fatigue crack
growth: microstructural and environmental effects,
Fatigue Crack Growth Tresholds Concepts, TMS,
Philadelphia, Pa, D.L. Davidson and S. Suresh Eds, 3-25
(1983).
Wing tip, 300 MPa
16
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
SEM observations of the fracture
surfaces
Fatigue striations
Interstries : 8,91.10-8 m
1,96.10-7 m
3,85.10-7 m
1,04.10-6 m
Pristine, 250 MPa
Images MEB FEG Florence HAMON
17
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
CCT W40
Fatigue crack growth resistance
Mechanical polishing
1µm
R = 0.1
20 Hz
Optical observation of the crack
growth
Plot of fatigue propagation rate
function of Amplitude of the
stress intensity factor (∆K)
18
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Fatigue crack growth resistance
10
-5
10-5
Wing engine area L-T
wing_engine
wing tip L-T
●Wing engine area T-L
wing tip T-L
wing tip L-T
Wing
tip L-T
● Wing
wing tip tip
T-L T-L
■
■
pristine L-T
pristine L-T
da/dN (m/cycle) LT1
10
da/dN (m/cycle) T-L
-6
-6
da/dN (m/cycle)
NASGRO T-L
NASGRO L-T
10
-7
10
da/dN (m/cycle) L-T
-7
10
Pristine material L-T
NASGRO T-L
--- NASGRO L-T
10
-8
10-8
5
6
7
8
9 10
20
∆K (MPa x m )
1/2
30
5
6
7
8 9 10
∆K (MPa x m
20
1/2
)
19
30
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Analysis of fatigue data
EIFS (Equivalent Initial Flaw Size) type approach [14] using the AFGROW
software package and the NASGRO crack growth law:
Estimation of the initial defect size leading to fracture in a number of
cycles equal to the experimental fatigue (Exemple : 21647 cycles vs. 21658
cycles exp)
Surface or edge
corner
[W. S. Johnson, “The history, logic and uses of the
Equivalent initial Flaw Size approach to total fatigue life
prediction,” Procedia Engineering, vol. 2, no. 1, pp. 4758, 4//, 2010
20
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Crack growth rates
da/dN or interstriation spacing (m)
10
-5
Pristine
Wingtip
AFGROW
10
-6
10
-7
σ
=250MPa
max
10
-8
0
5 10
-4
1 10
-3
1,5 10
-3
2 10
-3
2,5 10
-3
3 10
-3
crack depth (m)
21
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Initial defect size
100µm
Wing tip, 400 MPa
Initial defect size: 85 x 85 µm²
AFGROW : 90,5 x 90,5 µm²
22
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Secondary initiation sites
Pristine, 300MPa
Engine area, 400MPa
Wing tip, 300MPa
Wing tip, 400MPa
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Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Initial defect size
Experiments
σmax (MPa)
Specimen
Afgrow computations
Defect Size (µm)
Localisation
Nf
c
Defect Size (µm) a=c
Nf
c
FPE-RL-09
face
30,5
28,5
309710
55,8
309900
FPE-RL-11
corner
54,5
60,6
161488
82,1
161450
FPE-RL-01
face
88,7
38,7
71317
89,8
71345
Pristine
250
300
400
FPE-RL-05
face
90,9
54,5
93912
69,6
93925
FPE-RL-03
corner
56,6
56,6
25466
76,4
25476
Average
64,24
47,78
74,74
FPE-IL-07
internal ?
6434198
-
-
FPE-IL-09
corner
93
27,9
185003
73,9
185020
FPE-IL-01
edge
-
-
78298
82,1
78282
FPE-IL-06
edge
-
-
81579
78,6
81611
FPE-IL-03
corner
83,3
83,3
21658
90,5
21647
FPE-IL-04
edge
-
-
21352
97,3
21358
Average values
88,15
55,6
FPE-IL[5-8]-05
edge
-
-
268202
42,2
268188
FPE-IL[5-8]-07
corner
83,3
83,3
114763
76,2
114752
FPE-IL[5-8]-01
face
-
-
175572
40,3
175360
FPE-IL[5-8]-11
edge
58,8
58,8
81973
78,2
82019
FPE-IL[5-8]-06
edge
83,3
58,3
35438
57,6
35431
FPE-IL[5-8]-08
corner
72,9
62,5
40292
47,7
40297
Average values
74,575
65,725
Wing tip
250
300
400
84,48
Engine area
275
300
400
57,03
24
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Initial defect size
35
percentage of tested samples (%)
30
experimental
calculation
25
20
15
10
5
0
10
20
30
40
50
60
70
80
90
Initial defect size (µm)
25
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Initial defect size
100
Cumulated probability
80
experimental
calculation
60
40
20
0
0
20
40
60
80
100
120
140
Intial defect size (µm)
26
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Summary
No significant difference in fatigue resistance between AA2024T351 from wing panels of a decommissioned AIRBUS A320 aircraft
and a pristine alloy in:
•
•
•
Fatigue lives
Fatigue crack growth rates
Fracture modes
Not statistical → need of additional data obtained on several
aircrafts, from different fleets etc..
Interest of comparing fatigue properties under actual wing load
spectrum
27
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Artificial ageing
1.1
σ max / Re 0.2%
1
0.9
0.8
0.7
0.6
1.00E+04
1.00E+05
1.00E+06
Total cycles to failure
reference-t0
t55
t0
t177
t27
aging wing
+ additional data on fatigue resistance in the
presence of corrosion defects as a function of ageing
28
Residual fatigue properties of a 2024-T351 aluminium alloy from
the teardown of AIRBUS A320 wing panels after service
Thank you
Questions ?
29
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