电磁超声检测各向同性金属材料的弹性模量及声波模式转换

Test of Elastic Constants and Ultrasonic Wave Mode Conversion of Isotropic Metals by EMAT

介绍了一种利用电磁超声波检测(EMAT)各向同性金属材料弹性模量的方法,检测对象为CSK-ⅡA标准试样(材料为20钢),利用大功率电磁超声检测系统同时激发横波和纵波,横波和纵波的传播速度分别为3 241.20m·s-1和5 937.62m·s-1,进而得出杨氏模量和泊松系数分别为212.51GPa和0.288 1。推导出横波转为纵波的模式转换效率为9.5%,系统激发纵波的效率是系统激发横波效率的9.2%。该检测方法不需要耦合剂和打磨工件,检测表面可以有腐蚀缺陷和凹凸不平,避免了传统压电超声检测需要使用耦合剂而带来的检测误差,提高了测量精度和检测效率。

This paper presents a method to measure elastic constants of isotropic metals by Electromagnetic Acoustic Transducer（EMAT）.The tested part is a standard CSK-II A sample.The EMAT system generates longitudinal and transverse waves concurrently near the part surface.The measured longitudinal wave and transverse wave speeds are 5937.62 m·s-1 and 3241.20 m·s-1,respectively.The derived Young′s Modulus and Poisson′s ratio are 212.51 GPa and 0.288 1,respectively.The wave mode conversion efficiency is deducted to be 9.5%.The efficiency of longitudinal wave exciting is found to be 9.2% of that of transverse wave exciting.The presented method for elastic constant inspection shows high accuracy and great convenience with no couplant and with toleration to part′s surface roughness,rust and corrosion.