“Pipe organ” air-coupled broad bandwidth transducer

Botong Zhu, Benjamin Tiller, Alan Walker, James Windmill, Anthony Mulholland

Research output: Contribution to conferencePaper

Abstract

Background, Motivation and Objective
Air-coupled transducers are used to conduct fast non-contact inspections in NDT. Normally, the bandwidth of a conventional transducer can be enhanced, but with a cost to its sensitivity. However, low sensitivity is very disadvantageous in air-coupled NDT. This paper presents a methodology for improving the bandwidth of an air-coupled diaphragm transducer without sensitivity loss by connecting a number of resonating pipes of various length to a cavity in the backplate (see figure 1(a)). The design is inspired by the pipe organ musical instrument, where the resonant frequency (pitch) of each pipe is mainly determined by its length.
Statement of Contribution/Methods
The design, manufacture and experiment are divided into five steps: first, a fast 1D (in space) mathematical model is employed to ascertain the location of resonances and investigate the benefits of an increased number of pipes. Second, a slower but more accurate 3D finite element model provides the optimized parameters of the transducer. Third, a CAD model is built and a commercial stereolithography 3D printer is used to print the “pipe organ” backplate. Fourth, a passive diaphragm is attached onto the cavity/backplate. Finally, a 2D laser vibrometer is used to measure the average velocity of the diaphragm when applying an external sound source in order to estimate the bandwidth.
Results/Discussion
The average velocity of the passive diaphragm in the “pipe-organ” transducer is compared with the standard “cavity-only” transducer. The membrane velocity bandwidth increases with the addition of pipes emanating from the cavity. A common noise floor was defined for both devices as 6dB below the maximum average velocity of the pipe backed device (see figure 1(b)). The bandwidth of this new device was 2.3 times larger than the standard one. Further work is now underway to change the passive diaphragm to an active polyvinylidene fluoride (PVDF) diaphragm. This will allow the bandwidth of the transmission voltage response and the receiving voltage response to be calculated and compared with that of the standard device.
Original languageEnglish
Number of pages4
Publication statusPublished - 6 Sep 2017
Event2017 IEEE International Ultrasonics Symposium - Omni Shoreham Hotel, Washington, D.C., United States
Duration: 6 Sep 20179 Sep 2017
http://ewh.ieee.org/conf/ius/2017/ (Conference website)

Conference

Conference2017 IEEE International Ultrasonics Symposium
CountryUnited States
CityWashington, D.C.
Period6/09/179/09/17
Internet address

Fingerprint

organs
transducers
bandwidth
diaphragms
air
cavities
vibration meters
printers
sensitivity
electric potential
computer aided design
fluorides
resonant frequencies
inspection
mathematical models
lithography
methodology
membranes
costs
acoustics

Keywords

  • Air-Coupled
  • Broad Bandwidth
  • 3D Print
  • NDT/E
  • Ultrasonic Transducer
  • MUT

Cite this

Zhu, B., Tiller, B., Walker, A., Windmill, J., & Mulholland, A. (2017). “Pipe organ” air-coupled broad bandwidth transducer. Paper presented at 2017 IEEE International Ultrasonics Symposium, Washington, D.C., United States.
Zhu, Botong ; Tiller, Benjamin ; Walker, Alan ; Windmill, James ; Mulholland, Anthony. / “Pipe organ” air-coupled broad bandwidth transducer. Paper presented at 2017 IEEE International Ultrasonics Symposium, Washington, D.C., United States.4 p.
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Zhu, B, Tiller, B, Walker, A, Windmill, J & Mulholland, A 2017, '“Pipe organ” air-coupled broad bandwidth transducer' Paper presented at 2017 IEEE International Ultrasonics Symposium, Washington, D.C., United States, 6/09/17 - 9/09/17, .

“Pipe organ” air-coupled broad bandwidth transducer. / Zhu, Botong; Tiller, Benjamin; Walker, Alan; Windmill, James; Mulholland, Anthony.

2017. Paper presented at 2017 IEEE International Ultrasonics Symposium, Washington, D.C., United States.

Research output: Contribution to conferencePaper

TY - CONF

T1 - “Pipe organ” air-coupled broad bandwidth transducer

AU - Zhu, Botong

AU - Tiller, Benjamin

AU - Walker, Alan

AU - Windmill, James

AU - Mulholland, Anthony

PY - 2017/9/6

Y1 - 2017/9/6

N2 - Background, Motivation and ObjectiveAir-coupled transducers are used to conduct fast non-contact inspections in NDT. Normally, the bandwidth of a conventional transducer can be enhanced, but with a cost to its sensitivity. However, low sensitivity is very disadvantageous in air-coupled NDT. This paper presents a methodology for improving the bandwidth of an air-coupled diaphragm transducer without sensitivity loss by connecting a number of resonating pipes of various length to a cavity in the backplate (see figure 1(a)). The design is inspired by the pipe organ musical instrument, where the resonant frequency (pitch) of each pipe is mainly determined by its length.Statement of Contribution/MethodsThe design, manufacture and experiment are divided into five steps: first, a fast 1D (in space) mathematical model is employed to ascertain the location of resonances and investigate the benefits of an increased number of pipes. Second, a slower but more accurate 3D finite element model provides the optimized parameters of the transducer. Third, a CAD model is built and a commercial stereolithography 3D printer is used to print the “pipe organ” backplate. Fourth, a passive diaphragm is attached onto the cavity/backplate. Finally, a 2D laser vibrometer is used to measure the average velocity of the diaphragm when applying an external sound source in order to estimate the bandwidth.Results/DiscussionThe average velocity of the passive diaphragm in the “pipe-organ” transducer is compared with the standard “cavity-only” transducer. The membrane velocity bandwidth increases with the addition of pipes emanating from the cavity. A common noise floor was defined for both devices as 6dB below the maximum average velocity of the pipe backed device (see figure 1(b)). The bandwidth of this new device was 2.3 times larger than the standard one. Further work is now underway to change the passive diaphragm to an active polyvinylidene fluoride (PVDF) diaphragm. This will allow the bandwidth of the transmission voltage response and the receiving voltage response to be calculated and compared with that of the standard device.

AB - Background, Motivation and ObjectiveAir-coupled transducers are used to conduct fast non-contact inspections in NDT. Normally, the bandwidth of a conventional transducer can be enhanced, but with a cost to its sensitivity. However, low sensitivity is very disadvantageous in air-coupled NDT. This paper presents a methodology for improving the bandwidth of an air-coupled diaphragm transducer without sensitivity loss by connecting a number of resonating pipes of various length to a cavity in the backplate (see figure 1(a)). The design is inspired by the pipe organ musical instrument, where the resonant frequency (pitch) of each pipe is mainly determined by its length.Statement of Contribution/MethodsThe design, manufacture and experiment are divided into five steps: first, a fast 1D (in space) mathematical model is employed to ascertain the location of resonances and investigate the benefits of an increased number of pipes. Second, a slower but more accurate 3D finite element model provides the optimized parameters of the transducer. Third, a CAD model is built and a commercial stereolithography 3D printer is used to print the “pipe organ” backplate. Fourth, a passive diaphragm is attached onto the cavity/backplate. Finally, a 2D laser vibrometer is used to measure the average velocity of the diaphragm when applying an external sound source in order to estimate the bandwidth.Results/DiscussionThe average velocity of the passive diaphragm in the “pipe-organ” transducer is compared with the standard “cavity-only” transducer. The membrane velocity bandwidth increases with the addition of pipes emanating from the cavity. A common noise floor was defined for both devices as 6dB below the maximum average velocity of the pipe backed device (see figure 1(b)). The bandwidth of this new device was 2.3 times larger than the standard one. Further work is now underway to change the passive diaphragm to an active polyvinylidene fluoride (PVDF) diaphragm. This will allow the bandwidth of the transmission voltage response and the receiving voltage response to be calculated and compared with that of the standard device.

KW - Air-Coupled

KW - Broad Bandwidth

KW - 3D Print

KW - NDT/E

KW - Ultrasonic Transducer

KW - MUT

M3 - Paper

ER -

Zhu B, Tiller B, Walker A, Windmill J, Mulholland A. “Pipe organ” air-coupled broad bandwidth transducer. 2017. Paper presented at 2017 IEEE International Ultrasonics Symposium, Washington, D.C., United States.