Development of Non-contact Air Coupled Ultrasonic Testing system for reinforced concrete structure

Abstract

We have developed the V transmission system using for online scanning, insitu-defects testing and automatic detection by Non-contact Air Coupled Ultrasonic Testing (NAUT), NAUT with the ultra-high power square burst wave pulser & receiver. Square burst waves transmit and receive more powerful ultrasonic than pulse wave. It is easy to obtain the optimum detective condition by changing of frequency & numbers of waves. Therefore it is suitable for NAUT to require the powerful transmission and receiving. This paper mainly discusses the non-contact air-coupled ultrasonic testing method (abbr. V transmission method), which is based on the transmission mode but receives the reflected signals from the same side. Firstly, the basic principle of the air-coupled ultrasonic testing and the V transmission method was described. Then, it was focused on the velocity measurement by using the non-contact air-coupled ultrasonic method and detection of internal defects. The measured results for some application examples were shown, such as detection and imaging of the defects in the acrylic block with/without hole, which is very difficult by using traditional methods. Last, the propagation velocity in concrete and the imaging in reinforced concrete were measured.