Impact damage characterisation of fibre metal laminates by X-ray computed tomography
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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.
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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 1/18 FML impact damage characterisation Forward
- 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 2/18 FML impact damage characterisation Back Forward
- 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. 3/18 FML impact damage characterisation Back Forward
- 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 4/18 FML impact damage characterisation Back Forward
- 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 4/18 FML impact damage characterisation Back Forward
- 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 4/18 FML impact damage characterisation Back Forward
- 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. 5/18 FML impact damage characterisation Back Forward
- 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. 5/18 FML impact damage characterisation Back 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. 5/18 FML impact damage characterisation Back Forward
- 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. 6/18 FML impact damage characterisation Back Forward
- 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 7/18 FML impact damage characterisation Back Forward
- 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 7/18 FML impact damage characterisation Back Forward
- 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. 7/18 FML impact damage characterisation Back Forward
- 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/ 8/18 FML impact damage characterisation Back Forward
- 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 9/18 FML impact damage characterisation Back Forward
- 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. 10/18 FML impact damage characterisation Back Forward
- 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. 10/18 FML impact damage characterisation Back Forward
- 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. 10/18 FML impact damage characterisation Back Forward
- 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. 10/18 FML impact damage characterisation Back Forward
- 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. 11/18 FML impact damage characterisation Back Forward
- 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. 12/18 FML impact damage characterisation Back Forward
- 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. 12/18 FML impact damage characterisation Back Forward
- 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. 12/18 FML impact damage characterisation Back Forward
- 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. 13/18 FML impact damage characterisation Back Forward
- 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. 14/18 FML impact damage characterisation Back Forward
- 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. 14/18 FML impact damage characterisation Back Forward
- 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. 15/18 FML impact damage characterisation Back Forward
- 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). 15/18 FML impact damage characterisation Back Forward
- 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) 16/18 FML impact damage characterisation Back Forward
- 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. 17/18 FML impact damage characterisation Back Forward
- 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 18/18 FML impact damage characterisation Back