EMAT System Design Of Electromagnetic Ultrasonic Nondestructive Testing

With the field which the NDTE method is used in extending, The application of ultrasonic nondestructive testing techniques are increasingly being used,The coupling medium is required in traditional piezoelectric ultrasonic testing, so it's difficult be used in these situations. While the electromagnetic acoustic testing technology transmits and receives ultrasonic wave by the induction of electromagnetism, it has been extensively used in the high temperature, on-line detection and moving sample field and become the necessary complementarity to the traditional ultrasonic testing technology. In this article, we research on electromagnetic acoustic testing by theoretical analysis and experimental method.First of all, the theory of electromagnetic acoustic testing is analyzed systematically. The process of energy changing and transferring is mainly discussed. On the basis of this, the structure of Electromagnetic acoustic transducer is introduced, and the relationship between the type of ultrasonic wave and the transducer's structure is analyzed. And the factors that affect the sensitivity of the system made a brief analysis.Then, On the basis of theoretical analysis, Design a complete set of electromagnetic ultrasonic system. Whole system, including analog and digital two parts, Analog part of which includes four parts, including the transducer, transmitting circuit , the receiving circuit and Filter circuit. The digital circuit adopt EP1C6Q240C8 chip of ALTERA company as hardware platform for the development of digital systems, embedded NiosⅡsoft-core processors and a variety of peripheral modules, coupled with external Flash, SDRAM form an embedded processor system.The software of system use modular structure,comprises the main program, communication program,interrupt program and others function programms.Mainly including system initialization,channel selection,gain control,data gather, communications modules and so on.