空气耦合超声探头声场及其对检测的影响

Acoustic Field of Air-Coupled Ultrasonic Probe and Its Effect on Detection

搭建空气耦合超声探头声场的指向性测量系统,考察4种型号的空气耦合超声探头声场的指向性。对预制分层缺陷的复合材料试样进行检测,分析了声场对检测结果的影响。结果表明,低频率、平探头的声场能量高,指向性较差,而高频率、聚焦探头声场能量低,指向性好,检测横向分辨率高。在保证穿透能力的前提下,应尽量选择后者。根据探头声场分布情况,合理调整检测距离,使被检材料位于探头的焦区内,也能够提高检测灵敏度。

A measurement system of air coupled ultrasonic field is set up, and the fiehl of 4 types of air coupled ultrasonic probe is detected. Composite specimens with embedded delamination are detected, effect of acoustic field on the detection results is analyzed. The results show that the low frequency and flat probe have high acoustic field energy and poor directivity, while the high frequency and focusing probe has low acoustic field energy, good direetivity and high lateral resolution. The latter should be chosen as long as the penetration capability is guaranteed. Detection distance should be determined according to the acoustic field distribution. The detection sensitivity ean be improved when the detected material is located in the focal region of the probe.