Study On Magnetic Flux Leakage Detection System Of Marine Steel-Plate

Ship navigation is under such special circumstances with serious external forces and complex internal structures that marine steel plates are easy to have a variety of defects, which result in the threat to normal operation of the ship. The existence of defects in steel-plate will seriously affect the stability and reliability of the ship. In order to ensure the safe of ships, marine steel-plate must be detected regularly, so that repaired or replaced the defective components for timely.This paper presented the theoretical model of magnetic flux leakage, the finite element simulation and testing to analyze flux leakage of marine steel-plate. Have introduced the mechanism of magnetic flux leakage, analyzed the affect of crack parameters (crack depth, width, lift-off value, etc.) by magnetic dipole model for different flaw forms, comed to the impact of the laws, and analyzed leakage magnetic field intensity and other relevant factors. Magnetization of different forms of comparative analysis and studied of this article, taked permanent magnet magnetization partial way, and selected NdFeB as permanent magnet materials, designed magnetic structure of the initial model, and studied the magnetization and job points.Through establishing the ANSYS finite element model, analyzed the magnet permanents,including thickness, width, magnetic gap, the author designed the most reasonable magnetic device; Viewed the distribution of magnetic line of force, the size of leakage magnetic field distribution, the magnetic flux leakage signals near the defects by the ANSYS simulation results, which provided a basis for the detection of magnetic flux leakage signal.According to the characteristics of steel-plate, selected magnetic flux leakage sensor array coil for signal acquisition by comparing. Testing on the experimental plate by electromagnetic detector. Obtained the results: positive and negative detection signal when hopping on at this time the location of sensor array location is defective. Hopping signals based on amplitude can determine the approximate depth range of, at the same time, the hopping signal that covered channels can show the defects information of breadth.This study which do main on the magnetic field leakage Magnetic flux leakage will provide basis for the development of instruments.