Preliminary Study On Electromaginetic Acoustic Transducer Inspection

The application of Electromagnetic Acoustic Transducer (EMAT) is a global leading technology in the field of None-destructive testing (NDT). It generates ultrasonic wave by electromagnetic without couple,It inspects the flaw on the surface or in the inside of variable shape for material metal sample. Compared with the traditional Ultrasonic Testing (UT) method,the EMAT can be used in not only traditional situation, but also high temperature environment, especially for those hidden in the shield.Summarizing the study home and abroad, This paper covered the basic theory of EMAT , got some designing principles of it. The paper built the model for the EMAT, and calculated the optimized parameter value. The prompting part is an important part. The EMAT efficiency is so low that it must have a big power amplifier. There are two types of the EMAT prompting: (1)Using the burst signal generator and the classic power amplify to prompt the probe. (2)Using the D class power amplifier to applicant the single PWM plus used in the D class for EMAT prompt. This paper designed the burst signal generator, the D class power amplifier of that talk above, and got perfect performance at the experiment.EMAT receiving is the reverse process of the prompting. Acoustic wave generated by the Lorentz force can be detected by the electromagnetic induction effect. The one generated by the magnetoelastic force can be detected by the inverse process of it.EMAT utilization in industry field is wide. This paper did a series of experiencements about MAT thickness gauging, track inspection, and comparing experience with traditional UT. Through the surface wave prompting and the magetoslatic force prompting this paper studied the EMAT track inspetion, and successed at the longitudinal and the circumferential track inspection.At the end of the paper, it sumarried the experience and study that talked above and aslo did a future plan of this project. Compared with the EMAT thickness gauging is more difficulty than the track detecting, so it is better to study the track detecting. after that it can study the EMAT thickness gauging.