High-speed noncontact acoustic inspection method for civil engineering structure using multitone burst wave

Sugimoto, Takashige; Sugimoto, Kazuko; Kosuge, Nobuaki; Utagawa, Noriyuki; Katakura, Kageyoshi

doi:10.7567/jjap.56.07jc10

Cited by 34 publications

(17 citation statements)

References 41 publications

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“…The notation (Φ200, 60) indicates that the diameter of a circular defect is 200 mm, and the embedded depth is 60 mm. As an emitted waveform, a single-tone burst wave [ 8 , 15 ] (frequency range 2000–6000 Hz, modulation frequency 200 Hz, interval time 50 ms, pulse width 3 ms, overall waveform length 1050 ms) was used. The signal of the vibration velocity at one measurement point was measured 5 times.…”

Section: Effects Of Normalization By Two Types Of Internal Defectsmentioning

confidence: 99%

Detection of Internal Defects in Concrete and Evaluation of a Healthy Part of Concrete by Noncontact Acoustic Inspection Using Normalized Spectral Entropy and Normalized SSE

Sugimoto

2022

Entropy

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Non-destructive testing, with non-contact from a remote location, to detect and visualize internal defects in composite materials such as a concrete is desired. Therefore, a noncontact acoustic inspection method has been studied. In this method, the measurement surface is forced to vibrate by powerful aerial sound waves from a remote sound source, and the vibration state is measured by a laser Doppler vibrometer. The distribution of acoustic feature quantities (spectral entropy and vibrational energy ratio) is analyzed to statistically identify and evaluate healthy parts of concrete. If healthy parts in the measuring plane can be identified, the other part is considered to be internal defects or an abnormal measurement point. As a result, internal defects are detected. Spectral entropy (SE) was used to distinguish between defective parts and healthy parts. Furthermore, in order to distinguish between the resonance of a laser head and the resonance of the defective part of the concrete, spatial spectral entropy (SSE) was also used. SSE is an extension of the concept of SE to a two-dimensional measuring space. That is, based on the concept of SE, SSE is calculated, at each frequency, for spatial distribution of vibration velocity spectrum in the measuring plane. However, these two entropy values were used in unnormalized expressions. Therefore, although relative evaluation within the same measurement surface was possible, there was the issue that changes in the entropy value could not be evaluated in a unified manner in measurements under different conditions and environments. Therefore, this study verified whether it is possible to perform a unified evaluation for different defective parts of concrete specimen by using normalized SE and normalized SSE. From the experimental results using cavity defects and peeling defects, the detection and visualization of internal defects in concrete can be effectively carried out by the following two analysis methods. The first is using both the normalized SE and the evaluation of a healthy part of concrete. The second is the normalized SSE analysis that detects resonance frequency band of internal defects.

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Section: Effects Of Normalization By Two Types Of Internal Defectsmentioning

confidence: 99%

Detection of Internal Defects in Concrete and Evaluation of a Healthy Part of Concrete by Noncontact Acoustic Inspection Using Normalized Spectral Entropy and Normalized SSE

Sugimoto

2022

Entropy

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“…The sound waves used by us are roughly divided into single-tone burst (STNB) wave 18) and multi-tone burst (MTNB) wave. 19,20) STNB wave is a waveform in which the center frequency is changed by a constant amount every interval time. The MTNB wave is a waveform without the former interval.…”

Section: Introductionmentioning

confidence: 99%

Research on improvement of defect detection accuracy by resonance judgment for noncontact acoustic inspection method by acoustic irradiation-induced vibration

Nakagawa

Sugimoto

et al. 2022

Jpn. J. Appl. Phys.

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Noncontact acoustic inspection methods using acoustic irradiation induced vibration and laser Doppler vibrometer that can perform defect exploration from a distance are being studied. This method has the feature that it can measure a wide range of measurement objects such as composite materials used for aerospace as well as concrete structures such as tunnels and bridges without contact. From the experimental results, it was found that the increase in noise level due to the decrease in the return light of the laser due to the condition of the measurement surface causes a decrease in the estimation accuracy of defect exploration. Therefore, it has been clarified that the detection accuracy of the defect position can be improved by devising a resonance judgement process for discriminating the signal and noise due to the resonance of the defect portion.

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“…Ultrasound technology that delivers a powerful sound wave with sharp directivity over a long distance in the air is required in the field of surface weather observation and nondestructive testing (NDT) [1][2][3][4]. To obtain high sound pressure at a long distance, a sound source with sharp directivity is necessary.…”

Section: Introductionmentioning

confidence: 99%

Development of an aerial ultrasonic sound source with a truncated cone-shaped reflective plate on a circular transverse vibrating plate

Uchiyama

Asami

Miura

2022

Acoust. Sci. & Tech.

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Ultrasound technology that delivers a powerful sound wave with sharp directivity over a long distance in the air is required. As a sound source for this purpose, authors devised an ultrasonic sound source with a new shape in which the opening area is smaller than that of the complex reflective plate, and a reflective plate whose size is equivalent to the area of the vibrating plate was mounted to it. This reflective plate is composed of a planar reflective plate and a truncated cone-shaped reflective plate. In this study, first, the directional characteristics of a circular transverse vibrating plate-type aerial ultrasonic sound source with an integrated rigid wall structure were examined. Next, the planar reflective plate and truncated cone-shaped reflective plate were analyzed to refine the design. Furthermore, a sound source equipped with these reflective plates was fabricated, and various acoustic characteristics were investigated. As the results, when the input power of the sound source was 30 W, the sound pressure was 293 Pa at the distance of 2 m. This is a unidirectional sound wave with a very intense sound pressure.

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High-speed noncontact acoustic inspection method for civil engineering structure using multitone burst wave

Cited by 34 publications

References 41 publications

Detection of Internal Defects in Concrete and Evaluation of a Healthy Part of Concrete by Noncontact Acoustic Inspection Using Normalized Spectral Entropy and Normalized SSE

Detection of Internal Defects in Concrete and Evaluation of a Healthy Part of Concrete by Noncontact Acoustic Inspection Using Normalized Spectral Entropy and Normalized SSE

Research on improvement of defect detection accuracy by resonance judgment for noncontact acoustic inspection method by acoustic irradiation-induced vibration

Development of an aerial ultrasonic sound source with a truncated cone-shaped reflective plate on a circular transverse vibrating plate

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