多基元聚焦空气耦合超声换能器*

文中针对空气耦合超声换能器及其在表面缺陷检测中的应用开展了研究。选用1-3型压电复合材料及双匹配层结构来实现超声换能器压电材料与空气之间声阻抗的逐渐过渡,提高压电材料/空气界面的声能量透射率进而提高空气耦合超声换能器的灵敏度。在此基础上研发制作了440 kHz多基元聚焦空气耦合超声换能器,并对其性能进行了测试。其焦距、焦宽及焦深分别为41.44 mm、1.14 mm和20.30 mm,灵敏度和带宽分别为-50 d B和20.2%。测试结果表明该空气耦合超声换能器具有优良的性能,利用该超声换能器可以有效检测材料表面缺陷。

Multi-element focused air-coupled transducer

This paper presents the design of air-coupled ultrasonic transducer and its application in surface crack detection. In order to improve the acoustic energy transmittance and the sensitivity of the transducer, 1-3 type piezoelectric composites stacking with two matching layers is adopted to overcome the enormous impedance mismatch between the piezoelectric composites and air. Based on this,S440 kHz multi-element focused air-coupled ultrasonic transducer is developed and manufactured. The actual measured focal length, focal width and focal depth of theSmulti-element focused air-coupled ultrasonic transducer are 41.44 mm, 1.14 mm and 20.30 mm,Srespectively, and its sensitivity and bandwidth are -50 dB and 20.2 %, respectively. The test results show that the air-coupled ultrasonic transducer has excellent performance, and can effectively detect the surface crack of the material.