厚壁管道线聚焦斜入射SV波EMAT辐射声场分析

Radiation sound field analysis of line-focusing angled SV wave EMATin thick-walled pipeline

由于圆弧型检测面的曲率半径对斜入射SV波EMAT辐射声场的影响规律尚不清楚,导致厚壁管道线聚焦斜入射SV波EMAT的缺陷检测能力、缺陷定量/定位精度出现偏差。建立了基于平面/凸面检测面的线聚焦斜入射SV波EMAT的辐射声场有限元模型,研究了凸面检测面的曲率半径、EMAT曲折线圈匝数、设计初始角等因素对辐射声场的主瓣峰值和主瓣宽度的影响规律,并与平面检测面进行了对比。结果表明,与平面检测面相比,凸面检测面起到聚焦超声波的作用,具体表现在聚焦侧主瓣峰值增加22.76%,主瓣宽度减小10.56%。在曲折线圈匝数超过28匝后,线圈匝数的增加对主瓣峰值加强作用有限;当曲率半径为1.485×10-1 m,线圈设计初始角为10°,曲折线圈匝数由10匝增加至28匝时,线聚焦SV波主瓣峰值增加102.56%,主瓣宽度减小57.99%。

Due to the indeterminacy of the influence of the curvature radius of the curved detection surface on the radiation sound field of angled SV wave EMAT, the deviations would occur in the defect detection capability and defect quantification/positioning accuracy of the thick-walled pipe line-focusing angled SV wave EMAT. The finite element model for the radiation sound field of line-focusing angled SV wave EMAT based on plane/convex detection surfaces is established, the influences of the factors such as the curvature radius of the convex detection surface, number of turns of meander-line coil and design initial angle on the main lobe peak and width are studied. Subsequently, the detection results for the convex detection surface are compared with those for the plane detection surface. The results show that compared with the plane detection surface, the convex detection surface plays a role of focusing ultrasonic wave, which is specifically manifested by the increase of the main lobe peak on the focusing side by 22.76% and the decrease of the main lobe width by 10.56%. When the number of turns of the meander-line coil is increased to more than 28 turns, the increase of the number of turns of the coil has a limited effect on strengthening the main lobe peak. When the curvature radius is 1.485×10-1 m, the design initial angle of the coil is 10 ° and the number of turns of the meander-line coil is increased from 10 to 28, the main lobe peak of the line-focusing SV wave increases by 102.56%, and the main lobe width decreases by 57.99%.