2006 Fiscal Year Final Research Report Summary
Construction of the life damage evaluation system for health monitoring
| Project/Area Number |
16560079
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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 |
Materials/Mechanics of materials
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| Research Institution | Tokyo University of Science |
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Principal Investigator |
KENJI Machida Tokyo University of Science, Mechanicheal engineering, Professor, 理工学部, 教授 (50089380)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Digital image correlation technique / Hybrid method / Infrared thermography / Heat conduction analysis / Infrared hybrid method / 3-D local hybrid method / Stress intensity factor / J integral |
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| Research Abstract |
1. Development of Displacement Measurement System by Digital Image Correlation Technique
(1) In the experiment using the specimen of SS400, the displacement analyses in 0.02 pixel or less of average errors with FEM were possible.
(2) The stress intensity factor was estimated by taking into consideration a high order deformation descending slope by less than 1% of the error with a three-dimensional finite element method.
(3) When taking even the secondary deformation gradient into consideration, the infinitesimal strain of about 0.02% was estimated by less than 10% of the error.
2. Analyses of a three-dimensional local hybrid method
The applicability of the three-dimensional local hybrid method in the structure with a surface crack subjected to a bending load was examined, and the following results were obtained.
(1) If a local model is enlarged simply, higher accuracy will not necessarily be acquired.
(2) A local model is not enlarged, but it is choosing suitable size and high accuracy can be
… More
acquired.
(3) If some optimum sizes of the local model are obtained, an approximation is built, and expecting optimum local model size can estimate a J integral value with sufficient accuracy, although the range is limited.
3. Analyses in Inverse Problem Heat-Conduction Analyses of Stress Field by Infrared Thermography
The following conclusions were obtained as a result of the investigation of the effect of thickness of a specimen and the frequency change at the time of an experiment on the heat conduction in the specimen.
(1) The error under the effect of heat conduction changes with setting out of the frequency at the time of measurement a lot. For highly precise analyses, it is necessary to use high frequencies, such as 20Hz and 25Hz.
(2) Even if it introduces the nonsteady-heat-conduction inverse analysis which eliminates the error of heat conduction, improvement in accuracy cannot be expected in the analyses by the thermoelastic stress measurement using a low frequency.
(3) About material with high heat conductivity (C1100), analytic accuracy falls with the increase in specimen thickness.
(4) In the thermoelastic stress measurement experiment in a high frequency, the error by the heat conduction of the direction of specimen thickness becomes so small that it can ignore. Less
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