| Project/Area Number |
60460141
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
計測・制御工学
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
SHIMIZU Hiroshi Tohoku University, 工学部, 教授 (00005175)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Ken Tohoku University, 工学部, 助手 (80134021)
NAKAMURA Kiyoshi Tohoku University, 工学部, 助教授 (00005365)
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| Project Period (FY) |
1985 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥6,600,000 (Direct Cost: ¥6,600,000)
Fiscal Year 1986: ¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1985: ¥4,100,000 (Direct Cost: ¥4,100,000)
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| Keywords | Nondestructive Evaluation / Noncontacting Ultrasonic Transducer / EMAT / ESAT / Electret / エレクトレット |
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| Research Abstract |
In the field of the ultrasonic non-destructive testing, EMATs (electromagnetic acoustic transducers) have attracted much attention because they can transmit and receive the ultrasound without directly contacting to materials under testing. The EMAT, however, should be driven with a high-power current source in order to obtain a high signal-to-noise ratio because of its quite high conversion loss (typically more than 70 dB). This usually brings about a feed through of the transmitting electric-pulse signal to the receiving circuit due to the electromagnetic coupling between the transmitting and the receiving transducers when the EMAT is applied to the pulse-echo method NDE.
The purpose of this study is to develop practical noncotacting ultrasonic transducers which are compact in size and have reduced internal cross-coupling so as to be applied to the pulse-echo method NDE.
In the fiscal years of 1985 and 1986, the following results have been obtained:
1. A new type of EMAT composed of an E-shaped magnetic core and a double-spiral flat coil has been fabricated and applied successfully to the testing of a gas-pipe.
2. An EMAT having high efficiency and high signal-to-noise ratio has been fabricated by using an E-shaped and a C-shaped magnetic cores arranged orthogonally to each other.
3. A combination of an ESAT (electrostatic acoustic transducer) and a non-biased EMAT has successfully been applied to the pulse-echo method NDE.
4. A new electret ESAT has been proposed which utilizes the pyroelectrically induced voltage in ferroelectric materials such as LiTa <O_3> as the bias source, and its performance has been experimentally examined.
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