Journal of Mechanical Science and Technology

The Korean Society of Mechanical Engineers (대한기계학회)
권호 표지

Image Enhancement of Simplified Ultrasonic CT Using Frequency Analysis Method

  • Kim, kyung-Cho (Center for Imaging Research and Advanced Materials Characterization, Physics Department University) ;
  • Hiroaki Fukuhara (National Research Institute for Metals, 1-2-1, Sengen, Tsukuba) ;
  • Hisashi Yamawaki (National Research Institute for Metals, 1-2-1, Sengen, Tsukuba)
  • Published : 2002.12.01
Download PDF
⟨ Previous Next ⟩

Abstract

In this paper, a simplified ultrasonic CT system, which uses the information in three directions, that is, 90°, ＋45° and －45°about the inspection plane, is applied to the high strength steel, and the frequency analysis method for enhancing the C scan or CT image is developed. This frequency analysis method is based on the frequency response property of the material. By comparing the magnitudes in the frequency domain, the special frequency which shows a significant difference between the welded joint and base material was found and used to obtain a C scan or CT image. Experimental results for several kinds of specimens, having a welded joint by electron beam welding, a weld joint by arc welding, on a fatigue crack, showed that the obtained C scan or CT image has better resolution than the results of previous experiments using the maximum value of the received waveform.

Keywords

References

  1. Birks, A. S., 1991, Nondestructive Testing Handbook 7: Ultrasonic Testing, ASNT
  2. JlS G 3106, 1999, Rolled Steels for Welded Structures
  3. Kim, K. C., Fukuhara H. and Yamawaki, H., 2001, 'The Development of Simplified Ultrasonic CT System and its Application to the Evaluation of Weld Metal,' KSME International, Vol. 15, No. 1, pp. 52-60
  4. Matsumoto, S. and Kimura, K., 1971, 'Relation Between Grain Size and Attenuation Coefficient of Austenitic Stainless Steel and Iron,' J. JSNDI, Vol. 20, pp.283-291 (In Japanese)
  5. Nakajima, H., 2000, 'Tensile and Impact Properties of Low Ferritic Ultrafine-Grained Steels,' Current Advances in Materials and Processes-Report of the ISIJ Meeting, Vol. 13, p.454 (In Japanese)
  6. Papoulis, A., 1987, The Fourier Integral and its Applications, Mc Graw-Hill, p.81