Talk given at the 5th Industrial Computed Tomography Conference (ICT2014) in Wels, Austria on the 26th February 2014.
This paper presents the first 3D CT assessment of impact damage in coupon size CARALL fibre metal laminates. CT was applied to provide novel 3D insights as to the impact damage produced in both metal and polymer layers of FML.
For the metal layers, the presence of yielding/cracking can be assessed, visualised and localised in 3D. For the composite layers, the impact damage can be segmented and rendered in 3D, showing the different damage mechanisms involved (cracking and delamination).
The distance transform methodology was employed to obtain through thickness damage profiles. These profiles can be used to automatically separate the segmented impact damage based on damage type.
Impact damage characterisation of fibre metal laminates by X-ray computed tomography
1. FML impact damage
characterisation
Fabien Léonard
Introduction
FML background
Damage characterisation
Impact damage characterisation of fibre metal laminates
by X-ray computed tomography
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Fabien Léonard1 Yu Shi2 Costantinos Soutis3
Philip J. Withers1 Christophe Pinna2
Composite damage
Summary
Discussion
1 Henry Moseley X-ray Imaging Facility, The University of Manchester
2 Department of Mechanical Engineering (Aerospace), The University of Sheffield
3 Aerospace Research Institute, The University of Manchester
5 th Conference on Industrial Computed Tomography
Upper Austrian University of Applied Sciences
Wels, Austria, February 26 th 2014
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2. FML impact damage
characterisation
Fibre Metal Laminates
Fabien Léonard
Introduction
FML background
Damage characterisation
Experimental
Definition
Fibre Metal Laminates or FMLs are multi-layered materials based on a stacked
arrangement of aluminium alloys and fibre-reinforced composite materials.
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
FMLs take advantages of metal and fibre-reinforced composites, providing superior
mechanical properties to the conventional lamina consisting only of fibre-reinforced
lamina or monolithic aluminium alloys.
Composite damage
Summary
Discussion
FML lay-up.1
1
TU Delf website http://www.lr.tudelft.nl
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3. FML impact damage
characterisation
FML for aerospace applications
Fabien Léonard
Introduction
FML background
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
Metal/fibre applications in Airbus A380 airplane.2
2
A. Vlot & J.W. Gunnink; Fibre Metal Laminates, Kluwer Academic Publishers, Dordrecht, The
Netherlands, 2001.
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4. FML impact damage
characterisation
Importance of impact damage characterisation
Fabien Léonard
Introduction
Impacts are a relevant source of damage for aircraft throughout their life. Mainly:
FML background
high velocity impacts: mainly in-flight, like bird strikes and hail impacts
Damage characterisation
low velocity impacts: related to airport and maintenance operations like
dropping tools, cargo containers handling and crashes with airport vehicles
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
3
TU Delf website http://www.lr.tudelft.nl
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5. FML impact damage
characterisation
Importance of impact damage characterisation
Fabien Léonard
Introduction
Impacts are a relevant source of damage for aircraft throughout their life. Mainly:
FML background
high velocity impacts: mainly in-flight, like bird strikes and hail impacts
Damage characterisation
low velocity impacts: related to airport and maintenance operations like
dropping tools, cargo containers handling and crashes with airport vehicles
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
Leading edge of an horizontal stabilizer
dented by hail.3
3
TU Delf website http://www.lr.tudelft.nl
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6. FML impact damage
characterisation
Importance of impact damage characterisation
Fabien Léonard
Introduction
Impacts are a relevant source of damage for aircraft throughout their life. Mainly:
FML background
high velocity impacts: mainly in-flight, like bird strikes and hail impacts
Damage characterisation
low velocity impacts: related to airport and maintenance operations like
dropping tools, cargo containers handling and crashes with airport vehicles
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
Heavy damage on a stabiliser produced
by bird strike.3
Leading edge of an horizontal stabilizer
dented by hail.3
3
TU Delf website http://www.lr.tudelft.nl
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7. FML impact damage
characterisation
FML and X-ray CT
Fabien Léonard
Introduction
FML background
Damage characterisation
Experimental
Material and testing
Literature
Impact damage mainly characterised by sectioning or C-scan.
X-ray tomography mentioned4 but used only as detailed cross-section analysis
technique, no 3D information extracted.
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
4
K. Dragan, J. Bieniaś, et al.; Inspection methods for quality control of fibre metal laminates (FML) in
aerospace components. Composites, 12(4), 272-278, 2012.
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8. FML impact damage
characterisation
FML and X-ray CT
Fabien Léonard
Introduction
FML background
Damage characterisation
Experimental
Material and testing
Literature
Impact damage mainly characterised by sectioning or C-scan.
X-ray tomography mentioned4 but used only as detailed cross-section analysis
technique, no 3D information extracted.
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
Challenge
To have enough X-ray energy to penetrate fully the metal layers whilst still
obtaining a good contrast between the low density materials, i.e. polymer
composite matrix and cracks/voids.
4
K. Dragan, J. Bieniaś, et al.; Inspection methods for quality control of fibre metal laminates (FML) in
aerospace components. Composites, 12(4), 272-278, 2012.
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FML impact damage characterisation
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Forward
9. FML impact damage
characterisation
FML and X-ray CT
Fabien Léonard
Introduction
FML background
Damage characterisation
Experimental
Material and testing
Literature
Impact damage mainly characterised by sectioning or C-scan.
X-ray tomography mentioned4 but used only as detailed cross-section analysis
technique, no 3D information extracted.
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
Challenge
To have enough X-ray energy to penetrate fully the metal layers whilst still
obtaining a good contrast between the low density materials, i.e. polymer
composite matrix and cracks/voids.
This study
We demonstrate how CT can be employed to successfully assess impact damage in
FML in a three-dimensional non-destructive manner; and obtain information
conventional techniques cannot provide.
4
K. Dragan, J. Bieniaś, et al.; Inspection methods for quality control of fibre metal laminates (FML) in
aerospace components. Composites, 12(4), 272-278, 2012.
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FML impact damage characterisation
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10. FML impact damage
characterisation
Material and testing
Fabien Léonard
Introduction
FML background
Specimens:
Damage characterisation
Experimental
Material and testing
CARALL: CARbon fibre reinforced polymer/ Reinforced ALuminium Laminate
carbon fibre/epoxy layers (HTS40/977-2) with aluminium Al1050 layers
X-ray computed tomography
Results
2D data
2 different structures: CARALL 3-3/2-0.5 and CARALL 5-3/2-0.5
FML used as primary structures in aerospace applications
Metal damage
Composite damage
Summary
Discussion
Impact testing:
impact testing following ASTM D7136/D7136M-07 standard5
impact energies of 9.8 J, 19.6 J, and 29.4 J
simulates low velocity impact thin laminates experience during service
5
ASTM D7136/D7136M-07; Standard test method for measuring the damage resistance of a fibre-reinforced polymer matrix
composite to a drop-weight impact event, Philadelphia: American Society for Testing and Materials, 2007.
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FML impact damage characterisation
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11. FML impact damage
characterisation
Specimen structures
Fabien Léonard
Two CARALL structures are under investigation:
Introduction
FML background
Impact direction
Damage characterisation
Experimental
Structure 3-3/2-0.5 includes:
Aluminium
Material and testing
X-ray computed tomography
3 layers of Al
each layer is 500 µm thick
MTA 240
Results
0◦ ply
2D data
90◦ ply
Metal damage
Composite damage
2 fibre/epoxy layers
each ply is 250 µm thick
0◦ /90◦ fibre orientation
MTA 240
Summary
Aluminium
Discussion
MTA 240
MTA 240 used as adhesive between
metal and polymer
90◦ ply
0◦ ply
Al rolling direction aligned with 0◦
plies
MTA 240
Aluminium
CARALL 3-3/2-0.5
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12. FML impact damage
characterisation
Specimen structures
Fabien Léonard
Two CARALL structures are under investigation:
Introduction
FML background
Impact direction
Damage characterisation
Experimental
Material and testing
Structure 5-3/2-0.5 includes:
Aluminium
X-ray computed tomography
Results
2D data
3 layers of Al
each layer is 500 µm thick
MTA 240
0◦ ply
90◦ ply
90◦ ply
0◦ ply
Metal damage
Composite damage
Summary
Discussion
2 fibre/epoxy layers
each ply is 125 µm thick
0◦ /90◦ /90◦ /0◦ fibre orientation
MTA 240
Aluminium
MTA 240
0◦ ply
90◦ ply
90◦ ply
0◦ ply
MTA 240 used as adhesive between
metal and polymer
Al rolling direction aligned with 0◦
plies
MTA 240
Aluminium
CARALL 5-3/2-0.5
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13. FML impact damage
characterisation
Specimen structures
Fabien Léonard
Two CARALL structures are under investigation:
Introduction
FML background
Impact direction
Impact direction
Damage characterisation
Experimental
Aluminium
Material and testing
Aluminium
X-ray computed tomography
MTA 240
Results
MTA 240
0◦ ply
90◦ ply
90◦ ply
0◦ ply
0◦ ply
2D data
90◦ ply
Metal damage
Composite damage
MTA 240
Summary
MTA 240
Aluminium
Aluminium
Discussion
MTA 240
MTA 240
0◦ ply
90◦ ply
90◦ ply
0◦ ply
90◦ ply
0◦ ply
MTA 240
MTA 240
Aluminium
Aluminium
CARALL 3-3/2-0.5
CARALL 5-3/2-0.5
Both panels have the same total thickness.
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14. FML impact damage
characterisation
Data acquisition
Fabien Léonard
Introduction
FML background
Scanning was performed at the Henry Moseley X-ray Imaging Facility on the
Nikon Metrology 225/320 kV Custom Bay system:
Damage characterisation
Experimental
Sample dimensions:
45 × 45 × 3.5 mm (9.8 J) and
70 × 70 × 3.5 mm (19.6–29.4 J)
Material and testing
X-ray computed tomography
Results
2D data
Voxel size: 22.5 µm (9.8 J) and
34.7 µm (19.6 J and 29.4 J)
Metal damage
Composite damage
Summary
Target: Mo
Discussion
Voltage: 90 kV
Current: 110 µA
Filtration: 1 mm Al
Exposure time: 1000 ms
3142 projections
Nikon Metrology 225/320 kV Custom Bay.6
Acquisition time: 53’
6
Henry Moseley X-ray Imaging Facility website http://www.mxif.manchester.ac.uk/
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15. FML impact damage
characterisation
Data processing
Fabien Léonard
Introduction
The data visualisation and processing was performed with Avizo Fire version 7.17 .
FML background
Damage characterisation
The segmentation was based on manual seeding followed by a watershed algorithm.
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
The methodology of
through-thickness impact
damage characterisation has
been adapted from the work of
Léonard et al.8 , used for
assessing impact damage in
composite panels.
It is based on the damage
distance transform by regards to
a reference surface.
7
Avizo Fire specifications, Visualization Sciences Group website http://www.vsg3d.com/avizo/fire
F. Léonard, J. Stein, et al.; 3D damage characterisation in composite impacted panels by laboratory
X-ray computed tomography. 1st International Conference on Tomography of Materials and Structures, Ghent
(Belgium), July 1-5, 2013.
8
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16. FML impact damage
characterisation
Raw data
Fabien Léonard
Introduction
FML background
Slices show that the several damage modes relevant to FMLs can be identified:
1
aluminium yielding
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 XY plane
b) 5-3/2-0.5 XY plane
c) 3-3/2-0.5 XZ plane
d) 5-3/2-0.5 XZ plane
Examples of slice showing damage (impact face on top) for 10 J impact energy.
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17. FML impact damage
characterisation
Raw data
Fabien Léonard
Introduction
FML background
Slices show that the several damage modes relevant to FMLs can be identified:
1
aluminium yielding
2
shear-induced polymer matrix cracking
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 XY plane
b) 5-3/2-0.5 XY plane
c) 3-3/2-0.5 XZ plane
d) 5-3/2-0.5 XZ plane
Examples of slice showing damage (impact face on top) for 10 J impact energy.
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FML impact damage characterisation
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18. FML impact damage
characterisation
Raw data
Fabien Léonard
Introduction
FML background
Slices show that the several damage modes relevant to FMLs can be identified:
1
aluminium yielding
2
shear-induced polymer matrix cracking
3
interlaminar cracking (or delaminations)
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 XY plane
b) 5-3/2-0.5 XY plane
c) 3-3/2-0.5 XZ plane
d) 5-3/2-0.5 XZ plane
Examples of slice showing damage (impact face on top) for 10 J impact energy.
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FML impact damage characterisation
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19. FML impact damage
characterisation
Raw data
Fabien Léonard
Introduction
Slices show that the several damage modes relevant to FMLs can be identified:
1
aluminium yielding
2
shear-induced polymer matrix cracking
3
interlaminar cracking (or delaminations)
4
FML background
bending-induced tensile polymer matrix cracking
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 XY plane
b) 5-3/2-0.5 XY plane
c) 3-3/2-0.5 XZ plane
d) 5-3/2-0.5 XZ plane
Examples of slice showing damage (impact face on top) for 10 J impact energy.
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20. FML impact damage
characterisation
Damage in metal layers
Fabien Léonard
Introduction
FML background
Metal impact damage
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
Dent deepens and global
permanent plate flexure increases
with impact energy.
a) 3-3/2-0.5 at 10 J
Damage always maximum for
bottom Al layer
Necking appearing from 10 J and
cracking developing along the Al
rolling direction above 20 J.
a) 3-3/2-0.5 at 20 J
No quantitative data yet.
a) 3-3/2-0.5 at 30 J
Evolution of damage in metal layers.
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21. FML impact damage
characterisation
Damage in metal layers
Fabien Léonard
Introduction
Each Al layer can be assessed individually in 3D:
FML background
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
3-3/2-0.5 at 10 J.
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22. FML impact damage
characterisation
Damage in metal layers
Fabien Léonard
Introduction
Each Al layer can be assessed individually in 3D:
FML background
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
3-3/2-0.5 at 20 J.
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FML impact damage characterisation
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23. FML impact damage
characterisation
Damage in metal layers
Fabien Léonard
Introduction
Each Al layer can be assessed individually in 3D:
FML background
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
3-3/2-0.5 at 30 J.
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24. FML impact damage
characterisation
Damage in composite layers
Fabien Léonard
Introduction
FML background
Damage characterisation
The 3D rendering of the damage illustrates the different damage morphologies
obtained for the two structures:
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 (250 µm plies)
b) 5-3/2-0.5 (125 µm plies)
3D rendering of impact damage in composite layers for 10 J impact energy.
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25. FML impact damage
characterisation
Specimen profile
Fabien Léonard
Introduction
FML background
The full specimen profile is obtained to understand the location of the damage
within the fibre/epoxy layers:
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 (250 µm plies)
b) 5-3/2-0.5 (125 µm plies)
Full specimen profile for a 10 J impact energy.
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26. FML impact damage
characterisation
Specimen profile
Fabien Léonard
Introduction
FML background
The full specimen profile is obtained to understand the location of the damage
within the fibre/epoxy layers:
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 (250 µm plies)
b) 5-3/2-0.5 (125 µm plies)
Full specimen profile for a 10 J impact energy.
Most of the damage lies within the second composite layer, with clear differences
between the two structure.
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27. FML impact damage
characterisation
Damage profile of second composite layer
Fabien Léonard
Introduction
FML background
A more accurate location of the damage within the second composite layer is
obtained by taking the second Al layer as a reference for the distance transform:
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 (250 µm plies)
b) 5-3/2-0.5 (125 µm plies)
Damage volume profile with second (central) aluminium layer as reference.
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28. FML impact damage
characterisation
Damage profile of second composite layer
Fabien Léonard
Introduction
FML background
A more accurate location of the damage within the second composite layer is
obtained by taking the second Al layer as a reference for the distance transform:
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
a) 3-3/2-0.5 (250 µm plies)
b) 5-3/2-0.5 (125 µm plies)
Damage volume profile with second (central) aluminium layer as reference.
The damage profiles can be used to automatically segment the damage volume
based on the damage type (crack vs delamination).
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29. FML impact damage
characterisation
Separation of segmented impact damage
Fabien Léonard
Introduction
FML background
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
a) 3-3/2-0.5 (impact face on top)
b) 5-3/2-0.5 (impact face on top)
Discussion
c) 3-3/2-0.5 (impact face on bottom)
d) 5-3/2-0.5 (impact face on bottom)
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30. FML impact damage
characterisation
Summary
Fabien Léonard
Introduction
FML background
This paper presents the first 3D CT assessment of impact damage in coupon size
CARALL fibre metal laminates.
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
CT was applied to provide novel 3D insights as to the
impact damage produced in both metal and polymer
layers of FML:
metal: presence of yielding/cracking can be assessed,
visualised and localised in 3D
Composite damage
Summary
Discussion
composite: impact damage can be segmented and
rendered in 3D, showing the different damage
mechanisms involved (cracking and delamination)
The distance transform methodology9 was employed to obtain through thickness
damage profiles. These profiles can be used to automatically separate the
segmented impact damage based on damage type.
9
F. Léonard, J. Stein, et al.; 3D damage characterisation in composite impacted panels by laboratory
X-ray computed tomography. 1st International Conference on Tomography of Materials and Structures, Ghent
(Belgium), July 1-5, 2013.
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31. FML impact damage
characterisation
Discussion
Fabien Léonard
Introduction
FML background
Thank you!
Damage characterisation
Experimental
Material and testing
X-ray computed tomography
Results
2D data
Metal damage
Composite damage
Summary
Discussion
http://www.nickveasey.com
Fabien Léonard
fabien.leonard@manchester.ac.uk
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