Metal Plate Detection Technology Research Based On The Electromagnetic Ultrasonic Surface Wave

Electromagnetic ultrasonic testing technology compared with traditionalpiezoelectric ultrasonic testing technology has many advantages, such as no couplant,high temperature resistant, easy operation and adoption to the harsh detectionenvironment. In recent years, it becomes a hot research in the field of nondestructivetesting. At present, electromagnetic acoustic has been used in the detection of trainwheels, plate, aluminum and steel. The electromagnetic ultrasonic testing technology willscreen out inevitably defects of metal materials in the production process, Have toguarantee the quality of the product, to ensure the production security role.This paper studies on the surface wave principle of electromagnetic acoustic,propagation characteristics and especially on the surface wave of electromagneticacoustic. Research on the process of electromagnetic field and mechanical field,ultrasonic field three field interaction. Analysis of the excitation surface wave at the sametime produce oblique incidence SV waves on the impact of detection, And wavepropagation Angle and the relationship between the wire spacing.Using ANSYS finite element analysis software, Establish electromagnetic ultrasonicsurface wave transducer3d finite element simulation model, Analysis of surface wave onthe surface of aluminum plate transmission mechanism, The electromagnetic acousticproduced by EMAT is segmented to four processes: the electromagnetic field, eddycurrent, the Lorentz force and fluctuations, which can simplify the ideological of thefinite element solution. For electromagnetic surface wave in aluminum production andpropagation process of the simulation and calculation, The particle coil by lorentz forcesize and direction.Designed based on electromagnetic ultrasonic surface wave plate inspection system,EMAT using single polarity square permanent magnet, manual winding more turns andcoil and measured metal plate combination form. The number of incentive signal isadjustable, frequency adjustable burst signal. Due to the electromagnetic ultrasonic transducer for energy efficiency is low, receives the echo signal is weak, so receivingadopt two-stage amplification, can play a useful signal amplification, filter out noisefunction.In contrast test, verify and coil wire spacing on the surface wave signal, theinfluence of aluminum plate and steel plate surface wave defect detection experimentsshow that surface wave propagation phenomenon.