Design Of Aluminum Plate Thickness Based On Electromagnetic Ultrasound

Electromagnetic ultrasonic testing technology is an emerging nondestructive testing technology in recent years.Compared with traditional non-destructive testing technology,electromagnetic non-destructive testing technology is more suitable for high-speed on-line testing,non-contact testing and high temperature environment due to its advantages of non-contact and no coupling agent,Detection and other special testing environment.With the rapid development of China’s economic construction,the number of aluminum alloy plates needed in aerospace,petrochemical,transportation and other industries also rose linearly.Due to the limitation of technology and the use of wear and tear,it is inevitable that defects will occur in the plates.Therefore,it is of great theoretical significance and application value to test the EMAT of aluminum alloy sheet.Aiming at the problems of low energy conversion efficiency,weak echo signal and difficulty in receiving and processing of subsequent signals,this dissertation makes the following research:First,based on the Maxwell equation,the mathematical deduction of the relationship between physical quantities in the electromagnetic ultrasonic transducer is made.It includes the equations of the magnetic field of the permanent magnet,the dynamic equation of the pulse eddy current,the equations of equilibrium motion of the particles in the tested part,Wave signal receiving equation;laid the theoretical foundation for the structural design and simulation optimization of electromagnetic ultrasonic transducer.Second,aiming at the problem of low efficiency and difficult echo signal detection of electromagnetic ultrasonic transducer,the electromagnetic ultrasonic model and three-dimensional simulation are established.By using ANSYS finite element analysis software,the electromagnetic ultrasonic model and the three-dimensional simulation are constructed.The effects of excitation signal,coil spacing,lift-off distance and other factors on magnetic field and Lorentz force are studied in detail.Found the best electromagnetic ultrasonic transducer set this parameter.Greatly improve the EMAT energy conversion efficiency.Third,according to the special characteristics of electromagnetic ultrasonic transducer and its functional requirements,in the small,integrated design ideas under the guidance,based on the simulation results,the hardware design of the electromagnetic ultrasonic transducer is carried out.And this paper uses Multisim for hardware circuit simulation.Hardware components include excitation signal generation circuit,power amplifier circuit,echo signal amplification filter circuit,signal acquisition and storage circuit,impedance matching circuit.Constructed the electromagnetic ultrasonic transducer experimental platform which realizing the thickness measurement of aluminum plate.Fourth,follow-up processing of electromagnetic ultrasonic testing data is cumbersome and time-consuming.This paper presents a method of thickness measurement based on depth confidence network.Using Matlab simulation software to measure the thickness of the data training and testing.Realize the rapid classification of aluminum thickness measurement data processing.Achieve the purpose of automatic identification of the thickness which greatly speed up the detection efficiency.