2006 Fiscal Year Final Research Report Summary
Monitoring of nonlinear damage in structural systems based on waves
| Project/Area Number |
16560210
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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 | Kyoto Institute of Technology |
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Principal Investigator |
SONE Akira Kyoto Institute of Technology, Graduate School of Science and Technology, Professor, 工芸科学研究科, 教授 (20197015)
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| Co-Investigator(Kenkyū-buntansha) |
MASUDA Arata Kyoto Institute of Technology, Graduate School of Science and Technology, Associate Professor, 工芸科学研究科, 助教授 (90252543)
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| Project Period (FY) |
2004 – 2006
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| Keywords | structural health monitoring / damage detection / wave / nonlinear / modulation |
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| Research Abstract |
In this study, damage detection methodologies that identify and characterize the extent, location and the nonlinearity of the structural damages with nonlinear nature such as loose bolts, gaps, kissing bonds and breathing cracks have been developed. The outcome of the study are summarized as follows :
1. A damage detection method for a beam structure based on the traveling wave components separated from the random ambient vibration has been proposed. It has been concluded that, at least under a well-arranged clean measurement condition, the proposed method can remotely detect cracks with length of minimally 25% of the thickness of the beam by using arrayed sensors located away from the crack.
2. For a bolted beam structure, it has been confirmed that the wave separation method can detect the stepwise drop-off of the bolts by monitoring the height of the peaks in the reflection intensity map.
3. A remote monitoring method for a beam structure with a gapped support has been proposed in which the gap length has been successfully identified by estimating the relationship between the displacement and the reaction force at the support from the separated wave components at the sensor array.
4. An early damage detection method based on the nonlinear wave modulation and its application to loose bolt detection and crack monitoring have been proposed. It has been confirmed that early damages can be detected as the amplitude/phase modulation of the high frequency probe wave which is synchronous with the structural vibration. In order to characterize and evaluate the damages, a modulation surface has been defined using the low and high frequency components of the observed signal. Laboratory testing has been conducted to show that the differential geometric features of the modulation surface are promising as an indicator of early damages.
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