A theoretical model for predicting the ultrasonic signals in cylindrical waveguide generated by EMATs

Developing a numerical model that accurately predicts ultrasonic signals in cylinders without relying on the finite element (FE) method can significantly improve computational efficiency. However, existing models capable of predicting received ultrasonic signals by electromagnetic acoustic transducers (EMATs) in cylindrical structures remain limited. To address this gap, this paper presents a theoretical model for predicting ultrasonic signals in finite-length cylinders excited by EMATs. The model comprehensively incorporates the entire EMAT operation process, including the excitation, propagation, and reception of ultrasonic waves. Analytical expressions of the trailing pulses are first derived based on the Pochhammer-Chree theory, revealing that these pulses originate from the superposition of guided waves. Subsequently, a numerical model is developed to calculate the time-domain signals received by EMATs through modal analysis. The effectiveness and accuracy of the proposed model are validated through comparisons with FE simulations and experimental results. The findings demonstrate that the model can accurately predict the ultrasonic wave modes and key signal characteristics, including waveform, amplitude, and trailing-wave periodicity, under varying EMAT parameters. This study provides a fast and accurate approach for predicting and interpreting ultrasonic responses generated and received by EMATs in cylindrical structures.