Development of an automated contactless ultrasonic scanning measurement system for wavefield imaging of concrete elements

This paper presents development of an automated contactless ultrasonic scanning measurement system for ultrasonic wavefield imaging of concrete elements. The system uses an air-coupled ultrasonic transducer for sending and a multi-channel MEMS ultrasonic air-coupled sensor array for sensing and thus enables rapid acquisition of ultrasonic wavefield data. The system requires neither physical contact between the sensors and test specimens nor special surface treatment of the concrete. In the paper, the design of the MEMS ultrasonic sensor array and an interfacial circuit are described. The MEMS sensor array with the interfacial circuit are then integrated into an automated scanner, and a series of ultrasonic scanning measurements are performed on a laboratory-scale concrete sample. The ultrasonic wavefield data obtained from the scanning measurement tests are visually represented. The experimental results show that the MEMS sensor array and interfacial circuit enable acquisition of leaky ultrasonic wave signals from the concrete sample with high SNR and high spatial resolution can be achieved in the obtained ultrasonic wavefield images.