International Journal of Applied Electromagnetics and Mechanics - Volume 65, issue 1

Authors: Shi, Minxia | He, Cong | Zhang, Xuanrui | Qiu, Aici | Li, Junhao

Article Type: Research Article

Abstract: This paper enhanced the integration-type E&S model and the dynamic E&S model for integrating the impact of DC-biased field and eddy current on vector magnetic properties of electrical steel sheet. B and H of electrical steel sheet are measured under DC-biased and rotating fields. Based on the measured results, the databases of reluctivity and hysteresis coefficients of both the enhanced integration-type E&S model and the improved dynamic E&S model are established for predicting H waveform under any given operating condition. By comparing the H waveform calculated by the …enhanced integration-type E&S model and the improved dynamic E&S model with the experimental H waveform, it is found that both two models have good reliability and the improved dynamic E&S model has slightly better accuracy than the enhanced integration-type E&S model. Show more

Keywords: Electrical steel sheet, DC-biased magnetization, Eddy current, the E&S model

DOI: 10.3233/JAE-190095

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 1, pp. 171-179, 2021

Authors: Shi, Wenze | Chen, Weiwei | Lu, Chao | Cheng, Jinjie | Chen, Yao

Article Type: Research Article

Abstract: The interest in applying non-destructive testing to the examination of the flaw and measurement of the thickness in the metals at high temperatures is increasing as the metal processing becomes continuous. Based on this background, we designed a water-cooled shear wave Electromagnetic Acoustic Transducer (EMAT) with a surface cooling technique, and the conversion efficiency could be improved by surface cooling. We used the chirp pulse compression technique to process the raw ultrasonic wave signal without synchronous average. Besides, a large casting slab with coarse grains and a massive forging with high temperatures were chosen as the testing objects. Then, the …effect of the lift-off distance on the Signal-to-Noise Ratio (SNR) of ultrasonic signals from the EMATs operated in both the pulse-echo mode and pitch-catch mode was investigated. Subsequently, the ultrasonic signals were de-noised respectively by synchronous averages and pulse compression, and the noise reduction ability was compared. Finally, the EMAT was tested with the forging at different temperatures from 92 °C to 730 °C. The performance of the EMAT with the excitation of a tone-burst signal was also compared with the performance of the EMAT using pulse compression technique. Results show that the lift-off, SNR, range resolution, and inspection efficiency can be largely enhanced with the signal processing of chirp pulse compression to the ultrasonic wave signal with no synchronous averaging. When the forging’s temperature is 730 °C, the SNR of the compressed signal is comparable to the SNR of the signal processed with 64 synchronous averages, and the wave-packet duration can be reduced by 80.5%. The proposed EMAT detection technique is particularly suited for real-time measurement and high-temperature testing. Show more

Keywords: EMAT, pulse compression, lift-off, high-temperature testing, real-time measurement

DOI: 10.3233/JAE-201531

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 65, no. 1, pp. 181-196, 2021