In-situ observation technologies

Fig. 1 Small-size specimen tester for CT, designed in the laboratory

@Figure 1 is a view of a small-size specimen tester for CT, designed in our laboratory(Review paper 1). The tester may be as light as around 5 kg and can be used for tensile, compression and fatigue tests of up to 2 kN. A small polycarbonate cylinder that absorbs X-rays is used as the loading frame to prevent the support from being reflected on images. The tester can be operated from the outside of the experimental hatch during X-ray irradiation. To satisfy the requirements of a CT tester, a light-weight compressed-air actuator is used to stop displacements at deep-submicron precision (actually measured displacement: about 0.1ƒÊm) throughout the imaging period of about 30 minutes. This special tester has been used to observe behaviors of various materials, such as tensile deformations (Paper 1, 2, 4, 5, 6, 710, 12), initiation of cracks (Paper 13),crack propagation (Paper 8), and the behavior of compression failure(Paper 3,9,11).

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Fig. 2 Small-size hot specimen tester for CT, designed in the laboratory

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@The device shown in Fig. 2 is a small-size hot specimen tester for CT, which was also designed in our laboratory. It is as light as about 3 kg and can be used for tensile and creep tests at up to 600‹C. The loading frame of the tester is a small amorphous carbon cylinder, which absorbs X-rays and is not reflected on images. We have used this tester to observe the damage behaviors of aluminum at high temperatures.

Review paper

  1. H. Toda, T. Kobayashi, T. Ohgaki, Advanced in Visualization Techniques by High-resolution X-ray CT: Application to in-situ Measurement of Internal Local Mechanical Quantities of Materials, Zairyo-shiken-gijyutsu, Vol.48CNo.1C2004C5-10.

Research paper

  1. H. Toda, I. Sinclair, J.-Y. Buffiere, E. Maire, K.H. Khor, P. Gregson and T. Kobayashi, A 3D measurement procedure for internal local crack driving forces via synchrotron X-ray microtomography, Acta Materialia, Vol 52, No.5, 2004, 1305-1317
  2. L. Qian, H. Toda, K. Uesugi, T. Kobayashi, T. Ohgaki, and M. Kobayashi, Application of synchrotron X-ray microtomography to investigate ductile fracture in Al alloys, Applied Physics Letters, Vol. 87, 2005, 241907
  3. T. Ohgaki, H. Toda, M. Kobayashi, K. Uesugi M. Niinomi, T. Akahori, T. Kobayashi, K. Makii and Y. Aruga, In situ observations of compressive behaviour of aluminium foams by local tomography using high-resolution X-ray, Philosophical Magazine A, Vol. 86, No.28, 2006, 4417-4438
  4. H. Toda, S. Yamamoto, M. Kobayashi and K. Uesugi, Direct measurement procedure for 3-D local crack driving force using synchrotron X-ray microtomography, Acta Materialia, Vol.56, 2008, 6027-6039
  5. L. Qian, H. Toda, K. Uesugi, M. Kobayashi and T. Kobayashi, Direct observation and image-based simulation of three-dimensional tortuous crack evolution inside opaque materials, Physical Review Letters, Vol.100, No.11, 2008, 115505
  6. A. Weck, D.S. Wilkinson, E. Maire and H. Toda, Visualization by X-ray tomography of void growth and coalescence leading to fracture in model materials, Acta Materialia, Vol.56, Issue 12, 2008, 2919-2928
  7. M. Kobayashi, H. Toda, Y. Kawai, T. Ohgaki, K. Uesugi, D.S. Wilkinson, T. Kobayashi, Y. Aoki, M. Nakazawa, High-density three-dimensional mapping of internal strain by tracking microstructural features, Acta Materialia, Vol.56, Issue 10, 2008, 2167-2181
  8. H. Zhang, H. Toda, P.C. Qu, Y. Sakaguchi, M. Kobayashi, K. Uesugi, Y. Suzuki, Three-dimensional fatigue crack growth behavior in an aluminum alloy investigated with in situ high-resolution synchrotron X-ray microtomography, Acta Materialia, Vol.57, No.11, 2009, 3287-3300
  9. H. Toda, K. Minami, K. Koyama, K. Ichitani, M. Kobayashi, K. Uesugi, Y. Suzuki, Healing behavior of preexisting hydrogen micropores, in aluminum alloys during plastic deformation, Acta Materialia, Vol.57, 2009, 4391-4403
  10. H. Toda, T. Nishimura, K. Uesugi, Y. Suzuki, M. Kobayash, Influence of high-temperature solution treatments on mechanical properties of an Al-Si-Cu aluminum alloy, Acta Materialia, Vol.58, 2010, 2014-2025
  11. Q. Zhang, H. Toda, Y. Takami, Y. Suzuki, K. Uesugi, M. Kobayashi Assessment of 3D inhomogeneous microstructure of highly alloyed aluminium foam via dual energy K-edge subtraction imaging, Philosophical Magazine, Vol.90, No.14, 2010, 1853-1871
  12. H. Toda, E. Maire, S. Yamauchi, H. Tsuruta, T. Hiramatsu, M. Kobayashi, In situ observation of ductile fracture using X-ray tomography technique, Acta Materialia, Vo.59, No.5, 2011, 1995-2008.
  13. H. Toda, S. Masuda, R. Batres, M Kobayashi, S. Aoyama, M. Onodera, R. Furusawa, K. Uesugi, A. Takeuchi, Y. Suzuki, Statistical assessment of fatigue crack initiation from sub-surface hydrogen micropores in high-quality die-cast aluminum, Acta Materialia, Vol. 59, No.12, 4990-4998, 2011
  14. H. Toda, H. Oogo, K. Horikawa, K. Uesugi, Y. Suzuki, Y. Aoki, M. Nakazawa and M. Kobayashi, The true origin of fractures in structural metals, Acta Materialia, to be submitted.