Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures

The nondestructive inspection of concrete structures is indispensable for ensuring the safety and reliability of aging infrastructures. Ultrasonic waves having a frequency of tens of kHz are frequently used to reduce the scattering attenuation due to coarse aggregates. Such low frequencies enable th...

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Autores principales:	Yoshikazu Ohara, Kosuke Kikuchi, Toshihiro Tsuji, Tsuyoshi Mihara
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	low-frequency phased array ultrasonic imaging concrete crack-type defect delamination Chemical technology TP1-1185
Acceso en línea:	https://doaj.org/article/d7547f03724b4511bfa5a8b87f1c1dc1
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spelling	oai:doaj.org-article:d7547f03724b4511bfa5a8b87f1c1dc12021-11-11T19:02:56ZDevelopment of Low-Frequency Phased Array for Imaging Defects in Concrete Structures10.3390/s212170121424-8220https://doaj.org/article/d7547f03724b4511bfa5a8b87f1c1dc12021-10-01T00:00:00Zhttps://www.mdpi.com/1424-8220/21/21/7012https://doaj.org/toc/1424-8220The nondestructive inspection of concrete structures is indispensable for ensuring the safety and reliability of aging infrastructures. Ultrasonic waves having a frequency of tens of kHz are frequently used to reduce the scattering attenuation due to coarse aggregates. Such low frequencies enable the measurement of the thickness of concrete structures and detection of layer-type defects, such as delamination, whereas it causes a lack of sensitivity to crack-type defects. In this paper, to realize the ultrasonic phased array (PA) imaging of crack-type defects, we fabricated a low-frequency (LF) array transducer with a center frequency of hundreds of kHz. To avoid the crosstalk between piezoelectric elements and dampen the vibration of each element, we adopted soft lead zirconate titanate (soft PZT) with a low mechanical quality factor. Subsequently, we optimized the geometry of each piezoelectric element using a finite element method to generate a short pulse. After validating the design in a fundamental experiment using a single-element transducer, we fabricated a 32-element array transducer with a center frequency of 350 kHz. To show the imaging capability of the LF array transducer, we applied it to a concrete specimen with a delamination. As a result, the PA with the LF array transducer clearly visualized the delamination, which could not be visualized using the PA with a 2.5 MHz array transducer. Furthermore, we applied it to a more challenging defect, a slit, which is sometimes used to simulate crack-type defects. As a result, the PA with the LF array transducer clearly visualized a slit of 1 mm width and 40 mm height in a concrete specimen. Thus, we demonstrated the usefulness of the LF array transducer for inspecting crack-type defects.Yoshikazu OharaKosuke KikuchiToshihiro TsujiTsuyoshi MiharaMDPI AGarticlelow-frequency phased arrayultrasonic imagingconcretecrack-type defectdelaminationChemical technologyTP1-1185ENSensors, Vol 21, Iss 7012, p 7012 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	low-frequency phased array ultrasonic imaging concrete crack-type defect delamination Chemical technology TP1-1185
spellingShingle	low-frequency phased array ultrasonic imaging concrete crack-type defect delamination Chemical technology TP1-1185 Yoshikazu Ohara Kosuke Kikuchi Toshihiro Tsuji Tsuyoshi Mihara Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures
description	The nondestructive inspection of concrete structures is indispensable for ensuring the safety and reliability of aging infrastructures. Ultrasonic waves having a frequency of tens of kHz are frequently used to reduce the scattering attenuation due to coarse aggregates. Such low frequencies enable the measurement of the thickness of concrete structures and detection of layer-type defects, such as delamination, whereas it causes a lack of sensitivity to crack-type defects. In this paper, to realize the ultrasonic phased array (PA) imaging of crack-type defects, we fabricated a low-frequency (LF) array transducer with a center frequency of hundreds of kHz. To avoid the crosstalk between piezoelectric elements and dampen the vibration of each element, we adopted soft lead zirconate titanate (soft PZT) with a low mechanical quality factor. Subsequently, we optimized the geometry of each piezoelectric element using a finite element method to generate a short pulse. After validating the design in a fundamental experiment using a single-element transducer, we fabricated a 32-element array transducer with a center frequency of 350 kHz. To show the imaging capability of the LF array transducer, we applied it to a concrete specimen with a delamination. As a result, the PA with the LF array transducer clearly visualized the delamination, which could not be visualized using the PA with a 2.5 MHz array transducer. Furthermore, we applied it to a more challenging defect, a slit, which is sometimes used to simulate crack-type defects. As a result, the PA with the LF array transducer clearly visualized a slit of 1 mm width and 40 mm height in a concrete specimen. Thus, we demonstrated the usefulness of the LF array transducer for inspecting crack-type defects.
format	article
author	Yoshikazu Ohara Kosuke Kikuchi Toshihiro Tsuji Tsuyoshi Mihara
author_facet	Yoshikazu Ohara Kosuke Kikuchi Toshihiro Tsuji Tsuyoshi Mihara
author_sort	Yoshikazu Ohara
title	Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures
title_short	Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures
title_full	Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures
title_fullStr	Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures
title_full_unstemmed	Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures
title_sort	development of low-frequency phased array for imaging defects in concrete structures
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/d7547f03724b4511bfa5a8b87f1c1dc1
work_keys_str_mv	AT yoshikazuohara developmentoflowfrequencyphasedarrayforimagingdefectsinconcretestructures AT kosukekikuchi developmentoflowfrequencyphasedarrayforimagingdefectsinconcretestructures AT toshihirotsuji developmentoflowfrequencyphasedarrayforimagingdefectsinconcretestructures AT tsuyoshimihara developmentoflowfrequencyphasedarrayforimagingdefectsinconcretestructures
_version_	1718431673912131584

Development of Low-Frequency Phased Array for Imaging Defects in Concrete Structures

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