Non-destructive Detection of Defects in Carbon Fiber-Reinforced Carbon Matrix Composites Using SQUID(SQUIDs, <Special Section>Superconducting Electronic Devices and Their Applications)

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概要

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• Carbon fiber composites are increasingly used as structural materials because of their unique and advantageous characteristics. Carbon fiber reinforced carbon matrix composite (C/C) has the characteristics of high fatigue resistance, fracture toughness and heat resistance up to 3000 K, and is an important component of refractory tiles and nozzles in space shuttles. Useful nondestructive testing methods for C/C are now required. We have developed a SQUID-NDT system based on a nonmagnetic coaxial pulse tube cryocooler (PTC), a HTS-SQUID gradiometer and a field generator with ferrite cores that induces high currents in specimens with low electric conductivity. The cryostat with the PTC is compact, at 50 mm in diameter and 400 mm in height. It weighs a total of 4 kg. The system noise is 80 μΦ_0/Hz^<1/2> corresponding to 1.3 nT/m/Hz^<1/2> at 100 Hz. We used the system to investigate the usefulness of the SQUID-NDT in detecting flaws in C/C composites. Hidden cracks in C/C multi-layered specimens were detected up to depth of 15 mm. Hidden cracks in C/C-Al stacked sample was also clearly detected. In addition, we magnetically detected the mechanical breaking process of a C/C specimen under tensile load using the current injection method. For this study, a technique for visualizing current detouring defects was developed for detection of deteriorating areas in the specimen. The deteriorating area, identified from the current map, expands during breaking process and agrees with the results obtained by the microscopic observation of the breaking process. The interrupted current I_<int>, estimated by summing the detour current, clearly changed depending on the stage of the breaking process, suggesting that I_<int> may be applicable as good index for distinguishing each stage in the breaking process. It is concluded that a SQUID-NDT is applicable to C/C composites and advanced complex materials with low electric conductivity in addition to metallic materials.

• 社団法人電子情報通信学会の論文
• 2005-02-01

著者

• HATSUKADE Yoshimi

  The authors are with Toyohashi University of Technology

• Kasai Naoko

  The Authors Are With National Institute Of Advanced Industrial Science And Technology Aist

• Hatsukade Y

  The Authors Are With National Institute Of Advanced Industrial Science And Technology Aist

• TAKASHIMA Hiroshi

  The authors are with National Institute of Advanced Industrial Science and Technology, AIST

• Takashima Hiroshi

  The Authors Are With National Institute Of Advanced Industrial Science And Technology Aist

• Hatsukade Yoshimi

  The Authors Are With National Institute Of Advanced Industrial Science And Technology Aist

関連論文

• High-T_c SQUID Metal Detection System for Food and Pharmaceutical Contaminants(SQUIDs, Superconducting Electronic Devices and Their Applications)
• Non-destructive Detection of Defects in Carbon Fiber-Reinforced Carbon Matrix Composites Using SQUID(SQUIDs, Superconducting Electronic Devices and Their Applications)

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