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    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

    • 摘要: 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3 241.20 m ·s-1和5 937.62 m ·s-1,进而得出杨氏模量和泊松系数分别为212.51 GPa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。

       

      Abstract: 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.

       

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