A New Design of the Dual-Mode and Pure Longitudinal EMAT by Using a Radial-Flux-Focusing Magnet

Zhang, Xu; Li, Weiwen; Li, Bo; Tu, Jun; Liao, Chunhui; Wu, Qiao; Feng, Sheng; Song, Xiaochun

doi:10.3390/s22041316

Cited by 7 publications

(4 citation statements)

References 27 publications

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“…This Lorentz force is used to then induce the ultrasonic wave [23]. Both a static and dynamic magnetic field is generated on the surface of the specimen [22], which are both accounted for in the equation for magnetic flux density below.…”

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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“…Damadian et al [46] visualized tumours in living animals through field-focusing nuclear magnetic resonance (FONAR). In recent years, magnetic focusing was widely used in transcranial magnetic stimulation [47] (TMS), magnetic resonance imaging [48], magnetic drug targeting [49][50][51] (MDT), underground pipeline localization [52], metal soldering [53], metal surface detection [54] and quantum science [55].…”

Section: Of 29mentioning

confidence: 99%

Modelling, Linearity Analysis and Optimization of an Inductive Angular Displacement Sensor Based on Magnetic Focusing in Ships

Wang

et al. 2023

JMSE

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A sensor for measuring the crankshaft angle of the main engine in ships is designed. Compared with the existing crankshaft angle encoder, this design’s advantage is that there is no need to add a gear system at the free end of the crankshaft, reducing machining complexity. The purpose of providing high angle resolution over a wide speed range is achieved. Inductive angular displacement sensors (IADSs) require an eddy current magnetic field as a medium to generate the induced voltage. The induced voltage also requires a complex linearization calculation to obtain a linear relationship between angle and voltage. Therefore, a model of the inductive angular displacement sensor based on magnetic focusing (IADSMF) is proposed. Magnetic focusing is introduced into the IADS to replace the eddy current magnetic field with a focusing magnetic field. The main disadvantage of traditional IADSs, which is that they cannot reduce the eddy current magnetic field, is mitigated. An approximate square−shaped focusing magnetic field (12.4 × 12.4 mm2) is formed using the magnetic field constraint of the magnetic conductor. When the receiving coil undergoes a position change relative to the square−shaped focusing magnetic field, the voltage generated via the receiving coil is measured using the electromagnetic induction principle to achieve angular displacement measurement. A mathematical model of the IADSMF is derived. Induced voltages at different frequencies and rotational speeds are simulated and analyzed via MATLAB. The results show that frequency is the main factor affecting the induced voltage amplitude. The sensitivity of the IADSMF is 0.2023 mV/°. The resolution and measurement of the IADSMF range from 0.06° and 0–360°. Compared with a conventional planar coil−based IADS, the eddy current loss is reduced from 2.1304 to 0.3625 W. Direct linearization of the angular displacement with the induced voltage is achieved through designing a square−shaped focusing field and receiving coil. After optimizing the sensor structure with the optimization algorithm, the linearity error is 0.6012%. Finally, this sensor provides a theoretical basis and research ideas for IADS development in ships and navigation.

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“…To enhance the signal intensity, increasing the flux density of the static magnetic field is a direct and effective method. Zhang Xu et al [ 10 ] proposed a flux-focused EMAT composed of radial flux-focusing magnets, which provided a strong horizontal radial magnetic field and vertical axial magnetic field, significantly improving the amplitude of the studied wave. By adding a magnetic concentrator to the bottom of the magnet to guide and concentrate the static magnetic field of the permanent magnet, Liu et al [ 11 ] removed the unwanted A0 mode and then improved the signal purity and strength.…”

Section: Introductionmentioning

confidence: 99%

Antisymmetric Lamb Wave Simulation Study Based on Electromagnetic Acoustic Transducer with Periodic Permanent Magnets

Gao

Jia

2023

Sensors

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Due to its multi-mode and dispersion characteristics, Lamb waves cause interference to signal processing, which profoundly limits their application in nondestructive testing. To resolve this issue, firstly, based on the traditional EMAT, a horizontal polarization periodic permanent magnet electromagnetic acoustic transducer (HP-PPM-EMAT) was proposed. A 2-D finite element model was then developed to compare magnetic flux density, Lorentz force, and signal strength between the traditional EMAT and the HP-PPM-EMAT. The simulation results show that the HP-PPM-EMAT enhances the A0 mode Lamb wave (A0 wave) and suppresses the S0 mode Lamb wave (S0 wave). Finally, the influence of structural parameters of the HP-PPM-EMAT on the total displacement amplitude ratio of A0 and S0 was investigated using orthogonal test theory, and the width of magnet units was improved based on the orthogonal test. The results show that the total displacement amplitude ratio of A0 to S0 of the improved HP-PPM-EMAT can be improved by a factor of 7.74 compared with that of the traditional Lamb wave EMAT, which can produce higher-purity A0 mode Lamb waves.

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A New Design of the Dual-Mode and Pure Longitudinal EMAT by Using a Radial-Flux-Focusing Magnet

Cited by 7 publications

References 27 publications

Underwater communication acoustic transducers: a technology review

Underwater communication acoustic transducers: a technology review

Modelling, Linearity Analysis and Optimization of an Inductive Angular Displacement Sensor Based on Magnetic Focusing in Ships

Antisymmetric Lamb Wave Simulation Study Based on Electromagnetic Acoustic Transducer with Periodic Permanent Magnets

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