Bundesanstalt für Materialforschung und -prüfung BAM, 8.4 Acoustic and Electromagnetic Methods, Unter den Eichen 87, 12205 Berlin, Germany.
Health and Medical University, Olympischer Weg 1, 14471 Potsdam, Germany.
Sensors (Basel). 2023 Jan 26;23(3):1379. doi: 10.3390/s23031379.
Air-coupled ultrasound sensors have advantages over contact ultrasound sensors when a sample should not become contaminated or influenced by the couplant or the measurement has to be a fast and automated inline process. Thereby, air-coupled transducers must emit high-energy pulses due to the low air-to-solid power transmission ratios (10 to 10). Currently used resonant transducers trade bandwidth-a prerequisite for material parameter analysis-against pulse energy. Here we show that a combination of a non-resonant ultrasound emitter and a non-resonant detector enables the generation and detection of pulses that are both high in amplitude (130 dB) and bandwidth (2 µs pulse width). We further show an initial application: the detection of reflections inside of a carbon fiber reinforced plastic plate with thicknesses between 1.7 mm and 10 mm. As the sensors work contact-free, the time of flight and the period of the in-plate reflections are independent parameters. Hence, a variation of ultrasound velocity is distinguishable from a variation of plate thickness and both properties are determined simultaneously. The sensor combination is likely to find numerous industrial applications necessitating high automation capacity and opens possibilities for air-coupled, single-side ultrasonic inspection.
当样品不应受到耦合剂的污染或影响,或者测量必须快速且自动化的在线进行时,空气耦合超声传感器比接触式超声传感器具有优势。因此,由于空气与固体之间的功率传输比(10 比 1)较低,空气耦合换能器必须发射高能脉冲。目前使用的谐振换能器在带宽(材料参数分析的前提)和脉冲能量之间进行权衡。在这里,我们展示了一种非谐振超声发射器和非谐振探测器的组合,可以产生和检测幅度(130dB)和带宽(2µs 脉冲宽度)都很高的脉冲。我们进一步展示了一个初始应用:检测厚度在 1.7mm 到 10mm 之间的碳纤维增强塑料板内的反射。由于传感器无需接触即可工作,因此飞行时间和板内反射的周期是独立的参数。因此,可以区分超声速度的变化与板厚度的变化,并且可以同时确定这两个特性。这种传感器组合可能会在需要高自动化能力的众多工业应用中找到,并为空气耦合、单面超声检测开辟可能性。
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