Study on characteristics of radiation sound field of line-focusing angled SV wave EMAT

Abstract

The Electromagnetic acoustic transducer (EMAT) has valuable applications in ultrasonic nondestructive testing. The bidirectional radiation characteristics of the meander-line coil EMAT interfere with the location/ quantification of defects and affect the sensitivity of defect detection. It is the basis of defect detection to study the influence of the design parameters of the meander-line coil EMAT on its radiation sound field. Therefore, a finite element model for radiation sound field of line-focusing angled SV wave EMAT (LF-EMAT) is proposed to analyze the influences of meander-line coil turns and the initial angle on the main lobe peak and width of SV wave of the focusing side, as well as on the ratio of the peak value of the focusing side to that of the non-focusing side. Meanwhile, the experimental measurement and verification of the radiation sound field has been carried out. Results have shown that the lobe peak of the focusing side of LF-EMAT radiation sound field can reach about twice that of the non-focusing side. And as the number of meander-line coil turns increases, the energy and directivity of the focusing SV wave are enhanced, and the main lobe peak increases by more than 79.41%.