Simulation Analysis And Experimental Study Of Low Frequency Electromagnetic Detection Of Different Defects

Electromagnetic nondestructive testing is based on electromagnetic principle,and a nondestructive testing technology for risk assessment and defect detection of special equipment is carried out.At present,there are several methods,such as magnetic flux leakage,eddy current,metal magnetic memory,etc.,which have different technical advantages and disadvantages.This paper studies the low-frequency electromagnetic detection technology in recent years,including theoretical analysis,numerical simulation,experimental verification and field experiment application.The main research contents are as follows:1)Introduced the principle and application of several nondestructive testing methods,and briefly introduced the latest development of low-frequency electromagnetic technology at home and abroad.2)Using COMSOL software for low frequency electromagnetic field simulation analysis,preliminary deduced the low frequency electromagnetic field of eddy current and magnetic flux leakage internal coupling mechanism,and the different location,shape and size of defect of the low frequency leakage magnetic field distribution and the change of magnetic field intensity.3)Through the finite element simulation,the position,shape and size of the parameters that affect the signal strength of the low-frequency leakage magnetic field are studied.In this paper,using the method of control variables,the different forms of defects were simulated respectively,arrangement and analysis on the data obtained,get different defect characterization parameters and magnetic leakage field strength and low frequency magnetic flux leakage signal curve change rule and trend,so as to make the detection can be more accurate,quantitative defect recognition.4)On the basis of finite element analysis,formulated the defects of low frequency magnetic flux leakage testing whole experiment scheme,using the same control variable method,using artificial specimen experiment,analyzes the different parameters(defect location,defect shape and size)for detecting defects in low-frequency electromagnetic signal strength.The change rule of low-frequency leakage magnetic field is summarized,which provides reference for the low-frequency electromagnetic detection in engineering practice.5)Carry out the scene of the actual detection,in the detection of four condensate pipeline and detect the internal corrosion of different level point on a certain area of the lining of the corrosion defects,so as to verify the reliability test of low frequency electromagnetic detection technology as well as high sensitivity,high precision,lightweight portable detection speed and is applicable to the advantages of large area of damage detection.