| Project/Area Number |
11555180
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | The University of Tokyo |
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Principal Investigator |
ENOKI Manabu The University of Tokyo, Graduate School of Engineering, Associate Professor, 大学院・工学系研究科, 助教授 (70201960)
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| Co-Investigator(Kenkyū-buntansha) |
KISHI Teruo National Institute for Materials Science, President (Researcher), 物質・材料研究機構, 理事長(研究職)
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| Project Period (FY) |
1999 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥13,100,000 (Direct Cost: ¥13,100,000)
Fiscal Year 2001: ¥3,400,000 (Direct Cost: ¥3,400,000)
Fiscal Year 2000: ¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1999: ¥4,500,000 (Direct Cost: ¥4,500,000)
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| Keywords | Laser interferometer / Acoustic emission / Coatings / Micro Fracture / Waveform analysis / Non-desiructive / AE / レーザー / 干渉計 / 破壊 |
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| Research Abstract |
In this, research the method using laser interferometer, which can measure the absolute velocity of surface of materials in non-contact, was developed for acoustic emission (AE) transducer. We have demonstrated that this method could detect acoustic emission signals without contact and also applied it to the evaluation of fracture behavior of coating materials at elevated temperature. One of the problems of this method is to have less sensitivity compared with the conventional AE transducer using piezo elastic elements. The purpose of the research is to improve the system for AE measurement and increase the sensitivity for detection... The improvements were done in two ways. (1) The demodulator has been originally designed for laser Doppler vibrator. The frequency' characteristics of demodulator were focused for AE frequency and the noise components of systems were reduced by redesign of internal circuit. (2) Each channel of interferometer is affected by electromagnetic noise, mechanic
… More
al noise and so on. These noises can not be eliminated basically because AE signal is essentially transient phenomenon. We tried to reduce the noise components by the multi-channel detection of AE signals at the same point and numerical averaging of signals after recording. The method is possible to reduce the only noise component without loss of the characteristics of rising point and peak amplitude of AE wave form. These techniques of laser AE were applied to the thermal cycle tests of coating materials. Location of AE source was analyzed from multi-channel AE measurement and fracture mode was evaluated based on the simulation of elastic wave propagation by finite element method. Finally fracture mechanisms of coating materials were investigated. As the strength of coatings is affected by the initial defects due to plasma spray process, AE behavior was monitored during cooling process after plasma spray using laser AE method and the effect of process conditions on generation of defects was considered. Less
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