关键词: 超声无损检测, 自聚焦线阵, 声场计算, 高斯声束叠加

Abstract: Phased array ultrasonic technology has been developed rapidly in recent years and is widely used in industrial non-destructive testing. However, resolution on the long axis of the element is poor when linear array is employed. The traditional linear array cannot be focused on the long axis of the element, in order to overcome such problem the self-focusing linear array is developed recently. Self-focusing linear array is used to focused on both short and long axis of the element to acquire high resolution. To calculate the sound field of the self-focusing line array, the non-paraxial approximation Gaussian sound beam superposition method is developed. Compared with Rayleigh integral numerical method, the effectiveness of the method is verified. Furthermore, those parameters (focus intensity, focal size, focal length, etc.) of both traditional and self-focusing linear array with the variational steering angle is investigated using the proposed calculation method. The cylindrical workpiece is detected with self-focusing linear array transducer and the linear array transducer. The results show that the self-focusing linear array transducer can detect that the linear array transducer is difficult to detect axial defects. It is seen from theoretical and experimental results that the sound field of the self-focusing line array is calculated precisely with the proposed non-paraxial approximation Gaussian sound beam superposition method. The sensitivity is high on both short and long axis of the element of self-focusing line array.

Key words: ultrasonic nondestructive testing, self-focusing linear array, acoustic field calculation, Gaussian sound beam superposition