Integrated Non-destructive Evaluation Methods Research Of Pulsed Magnetic Flux Leakage

In the early form of defect usually exist stress concertration and the stress will gradually accumulate until the structural damage will be produced.According to the characteristics of pulse,the Pulse Magnetic Flux Leakage signal can be seperated into three parts,including metal magnetic memory used to assess the distribution of stress,magnetic Barkhausen niose used to quantitative the stress and the magnetic flux leakage used to quantitative the defect.Based on the analysis of principles and physical mechanism of three NDE methods,the similarity of their explaining mechanism and the correlation of the measured signals are investigated. Base on the analysis of pulsed responeses, the feasibility and implementation of obtaining three sigals at one are discussed.Simulation software Comsol is applied to analyse various influencing factors of pulse Magnetic Flux Leakage signal.The Integrated PMFL inspcetin system is designed and constructed, including incentive magnetic yoke, sensor selection, processing circuits, data acquisition system.The technology of PMFL and PMR was used to detect samples with various defects,including positioning, quantitative depth,identify defect types. Acccording to difference between time domain and Frequency band of different signal,achieved the separation and extraction of MMM signal and MBN signal. The reliability verification was carried out in order to ensuse that the methods is reliable and crediable. The change of Pulse magnetic Fulx Leakage signals under different load are analysed and the MMM and MBN to measure the stress, with the purpose of reflecting the information of stress are used.