超声爬波探头声场指向特性的试验研究

Study on the Spread Angle of the Sound Field of Ultrasonic Creeping Wave Probe

爬波检测是常规超声波检测的有力补充。由于爬波探头激发的声场具有多波型的特征,即在产生爬波的同时还会产生横波和头波,为全面了解爬波探头的声场特性,选用和制作了不同缺陷的对比试块进行测试。试验测得双晶片并列式爬波探头的声场指向特性图,获知该探头产生的爬波最大幅值方向与表面约呈15°,在33°左右激发的横波声压(4 mm横孔)比爬波主瓣高6dB,且该横波声压(大平底反射)比在30°左右激发的头波声压高9.5 dB。

Creeping wave testing is an effective supplement to conventional ultrasonic testing. Due to the fact that the sound field emitted by creeping wave probe has multi-wavemode characteristics, transverse and head waves are produced simultaneously with the creeping wave. For a comprehensive understanding of the characteristics of the sound field emitted by a creeping wave probe, comparative tests were made on some specially prepared reference blocks with different types of defects. Based on the results of the experiment, spread angle diagram of the sound field of a parallel bicrystal creeping wave probe was obtained, giving that angle between maximum amplitude direction of creeping wave produced by the probe and the surface was about 15°, and that the sound pressure of transverse waves （with φ 4 mm transverse hole） excited at about 33° was 6 dB higher than that of the main lobe of creeping waves, and that this transverse wave sound pressure （flat bottom reflection） was 9.5 dB higher than that of head waves excited at about 30°.