Research Pipeline Stress Detection Method Based On The Barkhausen Effect

Pipelines, bridges and other steel materials applied more widely than before, theferromagnetic material occupied an important position in the economic development of ourcountry and the world. Quality and safety testing of ferromagnetic material, as it is more andmore applications and more attention. Stress is present in the ferromagnetic material, thepresence or absence of a state the size of the material can not be visually observed. When theferromagnetic material to withstand internal stress reaches the maximum, the ferromagneticmaterial deformation will occur, this irreversible deformation used in everyday,such as oilpipelines will cause great harm. As a non-destructive testing method based on theBarkhausen effect method to detect stress, get more and more applications in practice.The existence of internal stress of ferromagnetic materials magnetic domain structure ofthe smallest unit, Barkhausen effect at the time of the magnetization of ferromagneticmaterials, due to the internal magnetic domain ferromagnetic material dislocation occurs,and it will release a high frequency signal, which is the Barkhausen signal. According to thestudy indicates that the Barkhausen signal and the stress of iron magnetic has a linearrelationship. In this paper plates for the detection of objects influence the stress on themagnetic domain structure of a ferromagnetic material, and the relationship between theBarkhausen signal and stress. Experiments using the electromagnetic detection principle, theU-shaped silicon tightly wound excitation coil tightly wound on rectangular silicon detectioncoil, with a sine wave signal is applied to both ends of the magnetic excitation coil steel inthe detection coil is placed on the plate with the regulator in the process of magnetization ofthe steel sheet, the detection coil will receive a signal containing the Barkhausen noise signa,as Barkhausen signal band of10KHz-1MHz, the received signal through a bandpass filtercircuit, filter out the clutter a complete Barkhausen signal; the Barkhausen signal is veryweak, in through the amplifier amplifies oscilloscope observation and recording.Experiments were subjected to the stress of the steel plates of different sizes weredetected, observe the size of its Barkhausen signal. The results show that: the internal steelexternal stress, causing the magnetic domain structure of a ferromagnetic material changes inthe magnetization process of dislocation generated magnetic domains Barkhausen signal,and with the change of stress, received Barkhausen signal also changes; the size of theexperimental study results ferromagnetic material with tensile stress suffered Barkhausen signal is proportional to the compressive stress is inversely proportional to the Barkhausensignal.Thus, by measuring the iron magnetic Barkhausen signals can achieve detection ofstress.