1. Design Method of Multiwavelength EMATs Based on Spatial Domain Harmonic Control.
- Author
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Zhai, Guofu, Li, Yongqian, Qin, Yiren, and Liu, Yueyi
- Subjects
- *
PULSE modulation , *ACOUSTIC transducers , *SPATIAL filters , *LAMB waves , *HARMONIC suppression filters , *ELECTRIC power filters - Abstract
Conventional electromagnetic acoustic transducers (EMATs) are generally only used to generate and detect guided waves with a single wavelength, which increases their sensitivity at that particular wavelength but limits their application scenarios and the accuracy of defect assessment. This article proposes a design method for multiwavelength EMATs based on spatial-domain harmonic control. First, the EMAT model is analyzed, where it is then outlined that the eddy-current density distribution of the specimen is equivalent to the spatial low-pass filtering of the coil-current density distribution. This shows that the multiwavelength guided waves can be achieved as long as the spatial distribution of the coil-current density contains those multiple harmonics that are desired. It is then proposed that the structure of the EMAT coil is equivalent to the spatial sampled pulse sequences of a spatial signal. The coil parameter design based on pulse modulation technology is proposed. Taking a dual-wavelength EMAT design for Lamb waves as an example, details of the coil parameter design are presented. The simulation and experiment with the dual-wavelength EMAT proved the correctness of the proposed method. Finally, an experiment with a three-wavelength EMAT demonstrated the feasibility of the proposed method in designing multiwavelength EMATs. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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