Abstract
Flexural ultrasonic transducers are robust and low cost sensors that are typically used in industry for distance ranging, proximity sensing and flow measurement. The operating frequencies of currently available commercial flexural ultrasonic transducers are usually below 50 kHz. Higher operating frequencies would be particularly beneficial for measurement accuracy and detection sensitivity. In this paper, design principles of High Frequency Flexural Ultrasonic Transducers (HiFFUTs), guided by the classical plate theory and finite element analysis, are reported. The results show that the diameter of the piezoelectric disc element attached to the flexing plate of the HiFFUT has a significant influence on the transducer's resonant frequency, and that an optimal diameter for a HiFFUT transmitter alone is different from that for a pitch-catch ultrasonic system consisting of both a HiFFUT transmitter and a receiver. By adopting an optimal piezoelectric diameter, the HiFFUT pitch-catch system can produce an ultrasonic signal amplitude greater than that of a non-optimised system by an order of magnitude. The performance of a prototype HiFFUT is characterised through electrical impedance analysis, laser Doppler vibrometry, and pressure-field microphone measurement, before the performance of two new HiFFUTs in a pitch-catch configuration is compared with that of commercial transducers. The prototype HiFFUT can operate efficiently at a frequency of 102.1 kHz as either a transmitter or a receiver, with comparable output amplitude, wider bandwidth, and higher directivity than commercially available transducers of similar construction.
Highlights
A IR-COUPLED ultrasonic transducers operating as either transmitters, receivers or transceivers have found many applications in fields such as robotics, automotive, communication, haptics, particle manipulation, flow measurement, and non-destructive testing and evaluation [1]–[12]
A titanium-capped high frequency flexural ultrasonic transducer (HiFFUT) is demonstrated, using the classical plate theory and finite element analysis (FEA) to guide the design of the transducer fabrication, and its performance has been characterized with comparison to a commercial 40 kHz FUT
Whilst the High Frequency Flexural Ultrasonic Transducers (HiFFUTs)’s resonant frequency is dominated by the resonant vibration modes of its titanium elastic plate, the piezoelectric disc attached to the plate has a significant and non-monotonic influence on resonant frequency, for the (1,0) mode of vibration
Summary
A IR-COUPLED ultrasonic transducers operating as either transmitters, receivers or transceivers have found many applications in fields such as robotics, automotive, communication, haptics, particle manipulation, flow measurement, and non-destructive testing and evaluation [1]–[12]. The parameters of an ultrasonic measurement system such as transduction efficiency, operating frequency, bandwidth, directivity, operating voltage (or current), and power consumption are all underpinned by the performance of the ultrasonic transducers. For air-coupled ultrasonic transducers that operate via the through thickness or radial resonant mode of a piezoelectric disc, a significant limitation is the mismatch of acoustic. Manuscript received December 16, 2019; revised February 18, 2020; accepted March 12, 2020. Date of publication March 20, 2020; date of current version June 18, 2020. The associate editor coordinating the review of this article and approving it for publication was Prof.
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