| Project/Area Number |
03555018
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
材料力学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
OKAMURA Hiroyuki Univ. Tokyo, Faculty of Engineering Professor, 工学部, 教授 (00010679)
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| Co-Investigator(Kenkyū-buntansha) |
TAKANO Tachio Univ. Tokyo, Faculty of Engineering, Assistant, 工学部, 助手 (10010852)
SAKAI Shinsuke Univ. Tokyo, Faculty of Engineering, Asoc.Prof., 工学部, 助教授 (80134469)
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| Project Period (FY) |
1991 – 1992
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| Project Status |
Completed (Fiscal Year 1992)
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| Budget Amount *help |
¥9,700,000 (Direct Cost: ¥9,700,000)
Fiscal Year 1992: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 1991: ¥8,500,000 (Direct Cost: ¥8,500,000)
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| Keywords | Ultrasonic measurement / Non-destructive evaluation / Damage accumulation / Creep / Fatigue / Ultrasonic attenuation / Back-scattering wave / 寿命予測 / クリ-プ損傷 / 自動測定 / タ-ビンロ-タ / ノイズエネルギ- |
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| Research Abstract |
1.Development of Ultrasonic probe with focusing sensor
An ultrasonic probe with focusing sensor was newly developed to improve the evaluation performance by back-scattering method for fatigue-creep damage. The probes were applied to damaged materials but no distinct improvement was observed compared with the normal probe type. It was shown that the improvement of measuring system is more important for the measuring accuracy.
2.Development of Ultrasonic measuring system
An Ultrasonic measuring system, which is composed of Work Station, pulser-receiver and digital oscilloscope, was developed. Aided by high performance of Work Station, the on-line real-time processing of the pressure load of the probe was developed using the DC solenoid. This greatly improves the measuring accuracy of ultrasonic properties.
3.Development of quasi-damaged specimen for creep-fatigue damage
Quasi-damaged materials with life ratio from 25% to 100% were made experimentally. The material is Cr-Mo-V Steel, which is often used as Rotor material in the electric power plant.
4.Development of evaluation method for damaged matcrials using inverse problem technique
Two evaluation methods for damaged materials were newly developed in addition to the normal ultrasonic attenuation method. One is a noise energy method which evaluates the damage by integrating the power spectrum of back-scattering wave and normalizing it. The other is a weighted noise energy method which also utilize integral of the spectrum but calculated under the weighted function.
5.Result
It was shown that the proposed weighted noise energy method has great advantage that the damage evaluation is not affected by the integral range of frequency. Moreover, the proposed noise energy method was found to have superior properties for the evaluation of damaged material compared with the normal ultrasonic attenuation method.
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