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Ultrasonic Wave and Light to Infrastructure
Shimadzu Review 75[3・4] (2018.12)
Abstract
In order to maintain and manage social infrastructure such as plants, roads, aviation, and railroads, it is necessary to appropriately determine the deterioration/damage of structures and members by periodic inspection. In recent years, there is a growing need for technologies to realize efficiency and labor saving of inspections, against the background of aging of structures, shortage of labor for inspection work, and problems in passing on skills.
The authors developed a technique to visualize defects near the surface of an object using ultrasonic waves and light. With this technology, minute displacement due to ultrasonic vibration is optically detected, and turbulence (discontinuity) of propagation of ultrasonic waves due to a defect is visualized, whereby a hidden defect on the surface of the object is detected with high sensitivity. In this article, in order to examine the applicability of this technology to infrastructure inspection applications, verification experiments using various samples and actual degraded structures were performed, and we report the results of detection of cracks under paint of painted concrete and steel members, which was conventionally difficult to detect by nondestructive means.
Keywords: Nondestructive inspection, Ultrasonic, Acoustic wave, Shearography, Infrastructure
1Robotics Unit, Technology Research Laboratory, Shimadzu Corporation, Kyoto, Japan
2Hanshin Expressway Company Limited, Osaka, Japan
3Department of Urban Management, Kyoto University, Kyoto, Japan
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