Research On Nondestructive Testing Technology Based On TMR Magnetic Sensor

As a contemporary detection technology,non-destructive testing technology can detect the surface and near surface of different materials,determine whether the material has defects,and accurately locate the position of the defect and the shape and size of the defect.The field plays an extremely important role,especially in heavy industry.Magnetic flux leakage detection technology is an important detection method for non-destructive testing technology and is widely used.In the field of magnetic flux leakage detection,quantitative analysis of defects has been a hot topic.In order to improve the detection sensitivity and better complete the quantitative analysis,this paper selects the TMR sensor to complete the magnetic flux leakage signal acquisition.The TMR sensor has high sensitivity,Iow power consumption,etc.It can also have a good output curve for weak magnetic field changes.Then the digital signal is pre-processed,and the spatial distribution of the horizontal component Bx and the vertical component By is analyzed,and the peak-to-peak characteristics of the Bx component peak and the By component are extracted.Based on Comsol software,the corresponding defect model is established,and the characteristics of horizontal component Bx and vertical component By of magnetic leakage field of defects with different geometric sizes are analyzed,and the quantitative relationship between the two components and the geometric size of defects is analyzed.At the same time,the influence of lift-off value and leakage magnetic field component is studied,and there is always a certain distance between the detecting probe and the surface of the tested part In the actual detection.In this paper,by constructing a circular hole-shaped periodic structure,the magnetic field of the detecting point is coupled to increase the magnetic field strength of the point at a certain height.Through simulation result analysis,it can be found that when the lift-off value reaches 3mm,a maximum magnetic field strength is generated,and when the constructed periodic structure radius reaches 5mm,the magnetic field strength reaches the maximum.Applying this structure to the design of the actual detection probe will greatly improve the detection sensitivity.Finally,the metal test piece is tested by the magnetic flux leakage detecting device in this paper,and qualitative and quantitative analysis is carried out to fit the relationship between the geometric feature of the defect and the leakage magnetic field component.The experimental results prove the accuracy of simulation model and result analysis.