2001 Fiscal Year Final Research Report Summary
Research on the Detection ofa Crack and Its Location Using ModalAnalysis and Signal Processing
| Project/Area Number |
12650227
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Dynamics/Control
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| Research Institution | Nagoya University |
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Principal Investigator |
ISHIDA Yukio Nagoya university, FacultyofEngineering, Professor, 大学院・工学研究科, 教授 (10092991)
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| Co-Investigator(Kenkyū-buntansha) |
KITAOKA Seiichiro Nagoya university, FacultyofEngineering, Professor, 工学部, 教授 (00023234)
INOUE Tsuyoshi Nagoya university, FacultyofEngineering, Lecturer, 大学院・工学研究科, 講師 (70273258)
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| Project Period (FY) |
2000 – 2001
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| Keywords | crack / rotor / fatigue / vibration diagnosis / resonance |
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| Research Abstract |
Since a periodic load to the rotor is inevitable during operation, rotating machinery is fatal to collapse due to fatigue. Many researchers investigated vibration characteristics of a cracked rotor for developing a diagnosis system. Most of the existing literatures crarifted resoannces, such as, harmonic resonances, subharmonic resonances, and superharmonic resonances, which occur due to the nonlinear characteristics mede by a crack. However, because the rated speed does not always coincedes with these resonance speeds, it is difficult to detect a crack from these resonances certainly.
In this study, we studied means which enables us to detect the occurrence of a crack and determine its location during the operation at a rotational speed separated from the resonance speeds. As the first step, we excited the rotor by a electrical magnet at various rotational speed and investigated the difference in the magnitude of the response and the spectra between a cracked rotor and a normal rotor. As a result, the following are clarified : (l) Resonances which areunique in a cracked rotor occur as the response to the periodic excitation. (2) Due to the coexistence of the parametric excitation due to a crack, the'nonlinearity due to a crack, and the gravity, these resoances occur when some specific relation holds among the rotational speed(a, the excitation frequency Q, and the natural frequency p. (3) It is possible to detect a crack if we pay attention to these resonances.
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