The Effect of Magnet-to-Coil Distance on the Performance Characteristics of EMATs

Wu, Yutang; Wu, Yunxin

doi:10.3390/s20185096

Cited by 5 publications

(7 citation statements)

References 24 publications

(30 reference statements)

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“…Electromagnetic acoustic transducers have the benefit of acting as both a transmitter and a receiver. Typical electromagnetic acoustic transducers are made up of a magnet, spiral coil, and a piece of aluminum [20]. Figure 8.…”

Section: Electromagnetic Acoustic Transducersmentioning

confidence: 99%

Underwater communication acoustic transducers: a technology review

Shams

2023

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2023

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This paper provides a comprehensive review on transducer technologies for underwater communications. The popularly used communication transducers, such as piezoelectric acoustic transducers, electromagnetic acoustic transducers, and acousto-optic devices are reviewed in detail. The reasons that common air communication technologies are invalid die to the differences between the media of air and water are addresses. Because of the abilities to overcome challenges the complexity of marine environments, piezoelectric acoustic transducers are playing the major underwater communication roles for science, surveillance, and Naval missions. The configuration and material properties of piezoelectric transducers effects on signal output power, beamwidth, amplitude, and other properties are discussed. The methods of code and decode communication information signals into acoustic waves are also presented. Finally, several newly developed piezoelectric transducers are recommended for future studies.

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Section: Electromagnetic Acoustic Transducersmentioning

confidence: 99%

Underwater communication acoustic transducers: a technology review

Shams

2023

Sensors and Smart Structures Technologies for Civil, Mechanical, and Aerospace Systems 2023

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“…EMATs are extensively used to generate Lamb waves because of the advantages provided by requiring no coupling agent, being noncontact, and enabling convenient detection [ 18 ]. However, compared with PZTs, EMATs have low transduction efficiency and, therefore, have a lower signal-to-noise ratio [ 19 , 20 , 21 ]. At the same time, when EMATs are used to generate Lamb waves, the multimode and dispersion characteristics of Lamb waves affect the detection [ 22 ].…”

Section: Introductionmentioning

confidence: 99%

Debonding Detection in Aluminum/Rigid Polyurethane Foam Composite Plates Using A0 Mode LAMB Wave EMATs

Yang

Zhang

et al. 2023

Materials

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Aluminum/rigid polyurethane foam composite plates (ARCPs) are widely used for thermal insulation. The interface debonding generated during manufacturing degrades the thermal insulation performance of an ARCP. In this study, the debonding of an ARCP, a composite plate with a porous and damped layer of rigid polyurethane foam (RPUF), was detected using A0 mode Lamb wave electromagnetic acoustic transducers (EMATs). The low energy transmission coefficient at the interface caused by the large acoustic impedance difference between aluminum and RPUF made the detection difficult. Based on these structural characteristics, an A0 mode Lamb wave with large out-of-plane displacement was used to detect the debonding. EMATs are preferred for generating A0 mode Lamb waves due to their advantages of being noncontact, not requiring a coupling agent, and providing convenient detection. A finite element simulation model considering the damping of the RPUF layer, the damping of the PU film at the interface, and the bonding stiffness of the interface was established. The simulation results indicated that the Lamb wave energy in the aluminum plate transmits into the RPUF layer in small amounts. However, the transmitted energy rapidly attenuated and was not reflected into the aluminum plate, as the RPUF layer was thick and highly damped. Therefore, energy attenuation was evident and could be used to characterize the debonding. An approximately linear relationship between the amplitude of the received signals and the debonding length was obtained. Experiments were performed on an ARCP using EMATs, and the experimental results were in good agreement with the simulation results.

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“…The main drawback of EMATs is their low efficiency. Consequently, they usually present a lower signal-to-noise ratio (SNR) than piezoelectric transducers, which can hinder the use of EMATs [9,10]. One way to alleviate this shortcoming is to guarantee maximum power transmission from the excitation electronics to the transducer [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…One important factor in the EMAT's design is its electrical impedance, and there are many factors that can affect it. Not only their coil geometry, but also the distance from the coil to the magnet, as explored by Wu et al [9]. The presence of a backplate between the transducer's components also affects its impedance, as exposed by Wang et al [15].…”

Section: Introductionmentioning

confidence: 99%

“…Some works aim to improve EMAT performance by studying the effects of physical changes in the transducers. Wu et al [9] studied the effect of magnet-to-coil distance on the performance characteristics of EMATs, concluding that the magnet-to-coil distance affects the magnetic flux density and eddy current density at the medium's surface and that, for a specific EMAT, there is an optimal magnet-to-coil distance that maximized its conversion efficiency over a range of lift-off distances. Wang et al [15] explored the effects that a copper backplate, positioned between the coil and magnet at various distances from the coil, can have on the EMAT impedance, the received pulse width, and the amplitude of thickness-measurement signals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A Simplified One-Parallel-Element Automatic Impedance-Matching Network Applied to Electromagnetic Acoustic Transducers Driving

Andrade,

Bazan,

Medeiros

et al. 2023

Automation

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Ultrasonic waves generated and received by electromagnetic acoustic transducers (EMATs) are advantageous in non-destructive testing, mainly due to the ability to operate without physical contact with the medium under test. Nevertheless, they present a main drawback of less efficiency, which leads to a lower signal-to-noise ratio. To overcome this, the L-network impedance-matching network is often used in order to ensure maximum power transfer to the EMAT from the excitation electronics. There is a wide range of factors that affect an EMAT’s impedance, apart from the transducer itself; namely, the properties of the specimen material, temperature, and frequency. Therefore, to ensure optimal power transfer, the matching network’s configuration needs to be fine-tuned often. Therefore, the automation of the laborious process of manually adjusting the network is of great benefit to the use of EMAT transducers. In this work, a simplified one-parallel-element automatic matching network is proposed and its theoretical optimal value is derived. Next, an automatic matching network was designed and fabricated. Experiments were performed with two different EMATs at several frequencies obtaining good agreement with theoretical predictions. The automatic system was able to determine the best configuration for the one-element matching network and provided up to 5.6 dB gain, similar to a standard manual solution and considerably faster.

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The Effect of Magnet-to-Coil Distance on the Performance Characteristics of EMATs

Cited by 5 publications

References 24 publications

Underwater communication acoustic transducers: a technology review

Underwater communication acoustic transducers: a technology review

Debonding Detection in Aluminum/Rigid Polyurethane Foam Composite Plates Using A0 Mode LAMB Wave EMATs

A Simplified One-Parallel-Element Automatic Impedance-Matching Network Applied to Electromagnetic Acoustic Transducers Driving

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