Research Of The Metal Plate Thickness Detection Technology Based On The Electromagnetic Ultrasonic Shear Wave

Electromagnetic ultrasonic is just a new type of non-destructive testing techniquesraised in recent decades. It is widely used in industrial production for its many advantagesof non-contact, coupling, removable online detection and can be detected in the hightemperature environment. Electromagnetic ultrasound producing a variety of modesflexibly in the online testing will get comprehensiveness and reliability evaluation of theequipment. Electromagnetic ultrasonic for thickness testing of the equipment can be ableto avoid the singularity of the crack detection defects and be Applied to a large area ofcorrosion detection, which will be more detailed and reliable for detection, if thicknessdetection and crack detection were focused on the same detection probe.This paper proceeds from a theoretical study of electromagnetic ultrasoniclongitudinal wave excitation principle combining software simulation and experiment todetermine the appropriate structure and size of the electromagnetic ultrasonic transducermodel. In order to avoid blind emulation, the orthogonal test optimization design methodwas used to be as a guide for transducer model simulation and determine the shape anddirection of the longitudinal wave propagation. During the simulation, the transducer coilshape, coil spacing, the number of different roots, as well as the size of the permanentmagnet a series of different factors on the conversion efficiency of the different impactwere researched respectively and summed up the transducer design standards: the highestefficiency of the transducer excitation, on the certain condition of the permanent magnet,there will be a certain relationship between coil area and lift-off distance, or a certainrelationship between area of coil area and the permanent magnets, on the certain conditionof lift-off distance of the coil. Accordingly to optimize the size of the model of thetransducer to detect the thickness on aluminum and steel respectively and obtain a stabledetection signal which had9echo times and the echo signal amplitude of optimizedelectromagnetic ultrasonic transducer was five times the echo signal amplitude of theoriginal by experiments. As the electromagnetic ultrasonic detection sensitivity is high, it is easy to introduce noise in the detection process. For the question of detection signalcontains noise, Weighted average wavelet threshold method was used for de-noisingprocessing and SNR was up to9.441which was2.6higher than traditional de-noisingmethods,and RMSE was0.0206.Simulations and experiments show that the shear wave can be used to detect the platethickness according the form and direction of the shear wave propagation obtained byANSYS finite element analysis and make Lorenz force as the optimization indexes tooptimize the transducer coil structure achieving the detection of the thickness for thedifferent material metal plate.