Research on a transmit-receive method of ultrasonic array for planar defects

The detection results have a strong dependence on the relative position of the transducer and planar defects. Therefore, detection of planar defects for complex structures has always been a difficult point in ultrasonic testing. In this paper, a transmit-receive method based on dual ultrasonic array transducers is put forward and described in detail. The influence of different positions of transmitting and receiving transducers on the planar defect detection method is analysed. Then, according to the structural characteristics of the specimen, a full coverage inspection scheme for butt weld of complex structure is established through the design of acoustic beam transmitting and receiving method. Combined with the flexible beam control method, the transmit-receive method of ultrasonic array can cover a larger detection range without moving the transducer, and the propagation distance of acoustic wave is shorter which can reduce the attenuation of acoustic energy. Additionally, a response simulation model of the ultrasonic array is established based on the finite-difference time-domain (FDTD) method. The echo signals of different wave modes are compared to optimize the focusing law. Finally, for the application on actual components, a set of transmitting and receiving transducers is designed for the ultrasonic array board that had 128 individual transceiver channels. The butt weld specimen with planar defects was fabricated and the practical experiments were conducted as well. The results show that the transmitreceive method of ultrasonic array can provide more accurate detection results in comparison with the conventional ultrasonic testing method using single transducer and greatly enhance the efficiency in planar defects detection.