Quantitative evaluation of defect depth in concrete structures using Fourier analysis for sequential thermal data

Shiro Nakamura; Takahide Sakagami; Shuusuke Harada; Shiro Kubo

doi:10.1117/12.779906

17 March 2008 Quantitative evaluation of defect depth in concrete structures using Fourier analysis for sequential thermal data

Shiro Nakamura, Takahide Sakagami, Shuusuke Harada, Shiro Kubo

Author Affiliations +

Proceedings Volume 6939, Thermosense XXX; 693910 (2008) https://doi.org/10.1117/12.779906
Event: SPIE Defense and Security Symposium, 2008, Orlando, Florida, United States

Abstract

In this paper, active thermography NDT method with active heating is developed for concrete structures. Active heating is effectively employed when temperature fluctuation on structure is small. As an estimation method of defect depth, the Fourier analysis of temperature descent curve after heating is employed. As the results, by using the phase delay distribution obtained from the Fourier analysis, the influence of the irregularity heating was reduced in comparison with the original temperature distribution. The phase delay image was also useful for determination of defect depth. Values of phase difference between delamination area and sound area show peaks at certain values of data processing period. These peaks can be directly related to defect depth. It is shown that three-dimensional shape of delamination defect can be accurately evaluated by the proposed technique.

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Shiro Nakamura, Takahide Sakagami, Shuusuke Harada, and Shiro Kubo "Quantitative evaluation of defect depth in concrete structures using Fourier analysis for sequential thermal data", Proc. SPIE 6939, Thermosense XXX, 693910 (17 March 2008); https://doi.org/10.1117/12.779906

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