Toshima-ku, Japan
Toshima-ku, Japan

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Ishikawa M.,Graduate University for Advanced Studies | Hatta H.,Japan Aerospace Exploration Agency | Habuka Y.,Krautkramer Japan Co. | Jinnai S.,Krautkramer Japan Co. | Utsunomiya S.,Japan Aerospace Exploration Agency
Advanced Composite Materials | Year: 2012

The influence of anisotropic thermal diffusivities on non-destructive testing of CFRP laminates using pulse phase thermography (PPT) was studied analytically. The results show that the optimum frequency for maximizing detectable depths of defects increases concomitantly with the increase in the ratio of the thermal diffusivities in the through-thickness direction to that in the in-plane direction (α′). Furthermore, the phase difference between sound and defective areas decreases significantly with decreased α′. These predicted tendencies were verified through experiments. Experimental results also demonstrated that defects of 10 mm in diameter can be detected up to around 5 mm depth in CFRP with lower α′, but only to around 1 mm in CFRP with higher α′. © 2012?Koninklijke Brill NV, Leiden.

Ishikawa M.,Graduate University for Advanced Studies | Ishikawa M.,Tokyo University of Science | Hatta H.,Graduate University for Advanced Studies | Hatta H.,Japan Aerospace Exploration Agency | And 3 more authors.
Infrared Physics and Technology | Year: 2013

Detectable defect depth by pulse phase thermography (PPT) is reportedly improved when using phase at low frequency. This study was conducted to identify mechanisms detecting deeper defects by the PPT, and to determine the optimum frequencies for detecting defects with various depths and sizes. One-dimensional and finite element analyses reveal that the optimum frequency decreases continuously with increasing defect depth, and that the amplitude of noise appearing in phase data decreases with decreased frequency. These engender a large signal-to-noise ratio for deep defects in a lower-frequency range. The analytical results were verified by experiments for a polymethylmethacrylate specimen having artificial defects. The experimental results at the optimum frequency demonstrated that defects with up to 5-6 mm depth were detected, which is a significant improvement compared with the reported detectable defect depth of 3.5 mm. © 2012 Elsevier B.V. All rights reserved.

Tanaka Y.,Ritsumeikan University | Tanaka K.,Ritsumeikan University | Sugiyama S.,Ritsumeikan University | Kurumi Y.,Shiga University of Medical Science | And 3 more authors.
Japanese Journal of Applied Physics | Year: 2011

A small ultrasonic probe capable of precise control of needle position is required for biopsies taken in abdominal surgery and laparoscopic surgery. We fabricated a small size ring-shaped probe with a through hole to insert the needle. The probe simultaneously detects the object in front of it, e.g., a lesion, and the tip of the needle. The error of the insertion depth measured by this detection was estimated to be less than 10.1% at a depth of more than 5mm when the inner diameter of the probe was 1.1mm and the outer diameter of the needle was 0.6 mm. The results of an experiment using a stomach wall specimen indicate that the position of the needle can be precisely controlled because the needle is directly below the probe. © 2011 The Japan Society of Applied Physics.

Nam K.W.,Pukyong National University | Kim J.W.,Korea Institute of Materials Science | Hinoki T.,Kyoto University | Kohyama A.,Muroran Institute of Technology | And 2 more authors.
Journal of Nuclear Materials | Year: 2011

Nondestructive evaluation (NDE) of ceramic matrix composites is essential to develop reliable ceramics for industrial applications. In this work, C-scan image analysis has been used to nondestructively characterize surface cracks in SiC/SiC composite ceramics. The possibility of detecting surface cracks was evaluated experimentally using ultrasonic equipment of μ-SDS with a probe of 170 MHz. The defocus method could detect the shape of surface cracks. As a whole, when the defocus method for the probe was used, we conclude that there is a good possibility of detecting surface cracks. © 2010 Elsevier B.V. All rights reserved.

Ishikawa M.,Tokyo University of Science | Hatta H.,Japan Aerospace Exploration Agency | Habuka Y.,Krautkramer Japan Co. | Fukui R.,Krautkramer Japan Co. | Utsunomiya S.,Japan Aerospace Exploration Agency
27th Annual Technical Conference of the American Society for Composites 2012, Held Jointly with 15th Joint US-Japan Conference on Composite Materials and ASTM-D30 Meeting | Year: 2012

A serious obstacle for practical application of conventional infrared thermographic non-destructive testing (IT-NDT) is that it can detect only near surface defects. In order to improve the depth of defects detectable by IT-NDT, pulse-phase thermographic technique was utilized in this study. Analytical calculations and experimental results shown that defects deeper than reported in previous papers could be detected by considering the optimum frequencies obtained in this study. In addition, further improvement of detectable defect depth was achieved by applying longduration heating instead of conventional instantaneous pulse heating.

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