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X-ray Computed Tomography: A New Dimension in Materials Science

This presentation was delivered at the IOM3 Young Persons Lecture Competition National Final held at The Armourers and Brasiers Hall in London on April 13 2011. I was the North West region entrant and won second place overall. The abstract of the presentation is shown below:

X-ray Computed Tomography: A New Dimension in Materials Science

Almost every area of materials has been revolutionised by the ability to obtain two-dimensional images with an increasing level of details. However, materials science being a three-dimensional science, techniques such as tomography -the art of reconstructing a sliceable virtual three-dimensional replica of the object from two-dimensional images- have become extremely popular.

X-ray Computed Tomography or XCT has been around for forty years but it is only in the last decade that the technique has seen dramatic changes through the combination of improved detector technologies for data acquisition and massively increased computing power for data analysis. These changes have allowed imaging to be extended from two spatial dimensions to three dimensions, the realm of X-ray computed tomography.

This lecture will present in details X-ray computed tomography: the background of the technique will be first introduced. Then, experiments performed within the Henry Moseley X-ray Imaging Facility will be presented to demonstrate the unique capabilities of XCT for each type of materials: metals, ceramics and polymers. Finally the latest developments will be introduced.

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X-ray Computed Tomography: A New Dimension in Materials Science

  1. 1. Outline Introduction Case studies Conclusion Appendix X-ray Computed Tomography: A New Dimension in Materials Science Fabien L´onard e Henry Moseley X-ray Imaging Facility The University of Manchester IOM3 Young Persons Lecture Competition National Final April 13 th 2011
  2. 2. Outline Introduction Case studies Conclusion AppendixOutline 1 Introduction Background Principles 2 Case studies Metals Polymers Biomaterials 3 Conclusion
  3. 3. Outline Introduction Case studies Conclusion AppendixBackgroundWhat is XCT? X-ray Computed Tomography or XCT is a non-destructive technique for visualising internal features within solid objects and for obtaining digital information on their 3D geometries and properties. XCT allows the complete structure of an object to be examined to give the precise size, shape and location of any internal feature or defect. Turbine blade Pitting corrosion Vascular cast
  4. 4. Outline Introduction Case studies Conclusion AppendixPrinciplesAcquisition Whilst illuminated by a X-ray cone beam, the sample is rotated through 360◦ on a high precision stage and a set of digital projections (i.e. 2D radiographs) are acquired at regular increments. http://www.phoenix- xray.com/en/company/technology/principles_of_operation/principle_060.html
  5. 5. Outline Introduction Case studies Conclusion AppendixPrinciplesAcquisition Whilst illuminated by a X-ray cone beam, the sample is rotated through 360◦ on a high precision stage and a set of digital projections (i.e. 2D radiographs) are acquired at regular increments.
  6. 6. Outline Introduction Case studies Conclusion AppendixPrinciplesAcquisition The gray levels in a projection correspond to differences in X-ray attenuation along the X-ray paths. X-ray attenuation is primarily a function of X-ray energy and the density and atomic number of the material being imaged.
  7. 7. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction   Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection.
  8. 8. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction   Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  9. 9. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  10. 10. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  11. 11. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  12. 12. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  13. 13. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  14. 14. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  15. 15. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  16. 16. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  17. 17. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  18. 18. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  19. 19. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  20. 20. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  21. 21. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  22. 22. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  23. 23. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  24. 24. Outline Introduction Case studies Conclusion AppendixPrinciplesReconstruction Reconstructing a 3D object from its 2D projections is complex and involves techniques in physics, mathematics, and computer science. Advanced algorithms and powerful computers are required to perform the necessary operation called backprojection. Filtering + backprojection
  25. 25. Outline Introduction Case studies Conclusion AppendixPrinciplesVisualisation Visualisation requires computers capable of handling huge data sets to obtain and visualise qualitative and quantitative information from material structure images. image processing image enhancement filtering and convolution feature extraction object separation Slice 3D rendering reverse engineering quantification and analysis phases, grains, particles, pores, cracks. . . counts, distributions, areas, volumes, and orientations Pore selection Volume distribution
  26. 26. Outline Introduction Case studies Conclusion AppendixMetalsTitanium fan blade Investigation of internal webbing distortion Objective: to determine quantitatively the distortion of the internal web structure Problem: difficulty to make precise measurement from a 2D radiograph regardless of the orientation http://www.rolls- royce.com/Images/brochure_Trent900.pdf
  27. 27. Outline Introduction Case studies Conclusion AppendixMetalsTitanium fan blade Investigation of internal webbing distortion Objective: to determine quantitatively the distortion of the internal web structure Problem: difficulty to make precise measurement from a 2D radiograph regardless of the orientation
  28. 28. Outline Introduction Case studies Conclusion AppendixMetalsTitanium fan blade Investigation of internal webbing distortion Objective: to determine quantitatively the distortion of the internal web structure Problem: difficulty to make precise measurement from a 2D radiograph regardless of the orientation
  29. 29. Outline Introduction Case studies Conclusion AppendixMetalsTitanium fan blade Investigation of internal webbing distortion Objective: to determine quantitatively the distortion of the internal web structure Problem: difficulty to make precise measurement from a 2D radiograph regardless of the orientation
  30. 30. Outline Introduction Case studies Conclusion AppendixMetalsTitanium fan blade Investigation of internal webbing distortion Direct measurement on 2D slice or comparison between 3D volume and CAD model (reverse engineering) Conclusion: the blades can be examined non destructively and their distortion assessed (magnitude and location).
  31. 31. Outline Introduction Case studies Conclusion AppendixPolymersAuxetic foam In situ tensile loading of conventional and auxetic polymeric foam Objective: to understand the auxetic behaviour of polymeric foam (negative Poisson’s ratio ν) Problem: difficult to describe the deformation of the structure in 3D during loading
  32. 32. Outline Introduction Case studies were cre Conclusionwere AppendixPolymers local) co localAuxetic foam b pss interacti inter solidi physica status larger n large In situ tensile loading of conventional and auxetic polymeric foam displ 50 displaceM S. difficulti diffic Conventional foam Auxetic foam edges of edge as sugge as su pss b solidi physica status A vo A 50 hexahed hexa S. McDonald et al.: In situ 3D X-ray microtomography study (C3D4)(C3D nation w natio defining defin HoweveHow element elem element elem required requ Fig Conclusion: better understanding of auxetic behaviour thanks to the v6.7 on v6.7 sho complete 3D description of the foam’s structure. eight exp eigh co $2 0000 $2 0 sha aux
  33. 33. Outline Introduction Case studies were cre Conclusionwere AppendixPolymers local) co localAuxetic foam b pss interacti inter solidi physica status larger n large In situ tensile loading of conventional and auxetic polymeric foam displ 50 displaceM S. difficulti diffic Conventional foam Auxetic foam edges of edge as sugge as su pss b solidi physica status A vo A 50 hexahed hexa S. McDonald et al.: In situ 3D X-ray microtomography study (C3D4)(C3D nation w natio defining defin HoweveHow element elem element elem required requ Fig Conclusion: better understanding of auxetic behaviour thanks to the v6.7 on v6.7 sho complete 3D description of the foam’s structure. eight exp eigh co $2 0000 $2 0 sha aux
  34. 34. Outline Introduction Case studies Conclusion AppendixBiomaterialsVelociraptor claw Investigation of the biomechanics of velociraptor claw Objective: to understand the form and function relationship. What were the claws used for: climbing or disembowelling? Problem: impossible to test a fossilised specimen
  35. 35. Outline Introduction Case studies Conclusion AppendixBiomaterialsVelociraptor claw Investigation of the biomechanics of velociraptor claw Objective: to understand the form and function relationship. What were the claws used for: climbing or disembowelling? Problem: impossible to test a fossilised specimen
  36. 36. Outline Introduction Case studies Conclusion AppendixBiomaterialsVelociraptor claw Investigation of the biomechanics of velociraptor claw Objective: to understand the form and function relationship. What were the claws used for: climbing or disembowelling? Problem: impossible to test a broken fossilised specimen
  37. 37. Outline Introduction Case studies Conclusion AppendixBiomaterialsVelociraptor claw Investigation of the biomechanics of velociraptor claw 1 Scanning of the claw: the inner structure can be revealed 2 Digital repair 3 Modelling
  38. 38. Outline Introduction Case studies Conclusion AppendixBiomaterialsVelociraptor claw Investigation of the biomechanics of velociraptor claw 1 Scanning of the claw 2 Digital repair: the broken parts of the claw can be realigned to give a brand new claw 3 Modelling
  39. 39. Outline Introduction Case studies Conclusion Appendix Biomaterials Velociraptor claw Investigation of the biomechanics of velociraptor claw MANNING ET AL. 1 Scanning of the claw 2 Digital repair 3 Modelling: the results reveal that the maximum stress is around 60 MPa (for a failure stress of 150-200 MPa) Fig. 6. Contour map of Mises stress (units in GPa) on (a) the outer surface of the claw and (b) through the mid-section.5. Velociraptor claw comprized of cortical and trabecular bone
  40. 40. Outline Introduction Case studies Conclusion Appendix Biomaterials Velociraptor claw Investigation of the biomechanics of velociraptor claw MANNING ET AL. 1 Scanning of the claw 2 Digital repair 3 Modelling: the results reveal that the maximum stress is around 60 MPa (for a failure stress of 150-200 MPa) Fig. 6. Contour map of Mises stress (units in GPa) on (a) the outer Conclusion: Velociraptor would surface ofbeen able to support its weight on have the claw and (b) through the mid-section. a very small contact surface of the claw while climbing.5. Velociraptor claw comprized of cortical and trabecular bone
  41. 41. Outline Introduction Case studies Conclusion AppendixSummarySummary XCT is a non-destructive technique for visualising internal features within solid objects, from fan blades to single carbon fibres. Entirely non-destructive 3D imaging ! Virtually any material can be analysed ! Little or no sample preparation required ! Resolution from 10 µm to 50 nm ! % Resolution limited by specimen size, high resolution requires small objects % Image artifacts can complicate data 49 million year old reconstruction and interpretation Huntsman spider in Baltic amber % Not all features have sufficiently large attenuation contrasts for useful imaging
  42. 42. Outline Introduction Case studies Conclusion AppendixDiscussionDiscussion Thank you! Fabien L´onard e fabien.leonard@manchester.ac.uk
  43. 43. Outline Introduction Case studies Conclusion AppendixAuxetic foamFE models from XCT data In situ tensile loading of conventional and auxetic polymeric foam Conventional foam Auxetic foam The study exemplifies the use of the tomography datasets as the basis for the creation of microstructurally faithful FE models.
  44. 44. Outline Introduction Case studies Conclusion AppendixVelociraptor clawClimbing or disembowelling? Investigation of the biomechanics of velociraptor claws
  45. 45. Outline Introduction Case studies Conclusion AppendixVelociraptor clawClimbing or disembowelling? Investigation of the biomechanics of velociraptor claws Tearing was never obtained regardless of the force applied. The experimental results are consistent with the finite element analysis.

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