Enhancement of Lamb-EMAT Signal Using a Modified One-Side Pitch-Catch Design

Abstract

This study presents a modified one-side pitch-catch electromagnetic acoustic transducer (EMAT), the optimized design improves the horizontal static magnetic field excitation and helps to enhance the generation and reception of the Lamb wave. A coupling model is applied to characterise and analyse the new design in detail. The model indicates that the optimized magnetic field with an increased peak flux density compared to the traditional magnetic configuration of EMAT. As a result, the transduction efficiency of the one-side pitch-catch design is dramatically improved ingeneration and reception process. Experiments verify that a measurement system using the modified one-side pitch-catch design is improved by a factor of 3.3, when compared to conventional one-side pitch-catch design.INDEX TERMS EMAT, Lamb waves, magnetic circuit optimization, one-side pitch-catch.

Orthogonal Optimal Design Method for Spiral Coil EMAT Considering Lift-off Effect: A Case Study

“…As a type of non-contact ultrasonic transducer, electromagnetic acoustic transducers (EMATs) have many advantages. Compared with conventional piezoelectric transducers, EMAT can generate ultrasonic waves directly at the surface of the specimen [6], [7], instead of transmitting the ultrasonic waves generated at the transducer to the specimen by utilizing couplant. Therefore, there can exist a gap, also called lift-off, between the coil in the EMAT and the specimen.…”

“…The main obstacles of the development of EMAT are the poor conversion efficiency and obvious lift-off effect, both of which will result in a low signal-to-noise ratio (SNR). A lot of research has been conducted to enhance the conversion efficiency [7], [10], [15]- [24], [28], [29]. Among the research, Huang proposed a new magnetic circuit configuration to enhance the conversion efficiency, and he found this configuration can transmit and receive a pure single A0 ultrasonic Lamb wave [15].…”

Electromagnetic Acoustic Transducer for Detection and Characterization of Hidden Cracks inside Stainless Steel Material

“…In recent years, the majority of EMAT researches have focused on cracks detection and to solve the problem of low conversion efficiency [13][14][15]. Whilst, the quantitative description of the defects didn't receive much concern.…”