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摘要:
Aiming at wide range health monitoring of plate structure, an omni-directional Lamb wave electromagnetic acoustic transducer (EMAT) was developed. Based on the theory of electromagnetic acoustic testing, the model of omni-directional Lamb wave EMAT for plate was established, and the expressions of received signal and equivalent sensitivity were obtained. Considering the relationship between structural parameters of EMAT and its equivalent sensitivity, seven omni-directional EMATs were fabricated, and their impedance matching was conducted. Experiment and theoretical analysis show that the designed EMAT can excite single S0 mode Lamb wave effectively and has selectivity to the lamb wave with given wavelength, and the tested center frequency agrees well with the designed value. Meanwhile, the measured sensitivities of EMATs with different ratios of inner and outer diameters are consistent well with the theoretical curves at same frequency. Experiment results prove that the designed EMATs have good consistency in the direction of 360°, which establishes a good foundation for the development of subsequent transducer array for plate structure monitoring.
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来源 :
Chinese Journal of Scientific Instrument
ISSN: 0254-3087
年份: 2010
期: 6
卷: 31
页码: 1387-1393