Based On The Coercivity Of Ferromagnetic Material Stress Detecting Technology

Iron and steel material such as pipeline and bridge is more and more widely applied, andit means the ferromagnetic materials occupy is more and more important in the nationaleconomy development status. Pipeline transportation energy has the advantages of low cost,high safety and stable supply, and bridge construction provides people a comfortable andconvenient transportation and travel conditions. It is the key to how to safeguard the steelstructures as in-service pipeline and bridge better, and to prevent the problem of stressconcentration caused by component failure effectively. In various magnetic parameters,Measurement of the coercivity force has smaller external disturbance, and there is importantsignificance of detection by measuring the coercivity force of material for the stressconcentration area.This paper mainly studies the basic theory of ferromagnetic material, includes aferromagnetic material, the magnetization process of domain structure technology, andcoercivity force. In order to fully prove that the coercive force is based on reliability of stressdetection, this paper has studied the effects the coercivity force in ferromagnetic materials bystress: deduced the stress effect on the magnetization of ferromagnetic materials orientation byformula; discussed the changes of ferromagnetic material stress caused by the internal energy,and The increase of the energy movement will impede domain wall, then the influenceferromagnetic material coercivity force. Take the sheet stress detection as the object of study,and by measuring the coercive force plate detect stress concentration zone. The experimentadopts the principle of electromagnetic detection, and detection probe is winding excitationcoil and the detection coil in the U type silicon steel sheet piling on, then It and the platemeasured part are formed into a closed magnetic circuit, So as to realize the measurement ofthe steel plate magnetic hysteresis loop, then obtained materials coercivity force. The excitingcoil is communicated with a sinusoidal AC signal of certain frequency and amplitude, andaccess to a sampling resistor at the same time, then Voltage sampling resistor at both ends ofthe received electrical signal proportional to the strength of the magnetic field H; the detectioncoil access integral circuit composed of resistor and capacitor, then get the electrical signalproportional to the intensity of magnetic induction of B by detecting a voltage across the capacitor. Two electrical signals were collected from X and Y input oscilloscope, and theexcitation current vary a cycle, then depict the hysteresis loop measured plate by theoscilloscope. The point of intersection of the hysteresis loop and the transverse coordinate isthe material of the coercivity force.The experiments were respectively detected by existence of different size stress steelplate, then observe the shape of the hysteresis loop, and get the coercivity force and compared.The experimental results show that: The external force make plate generate internal stress, andit results in a reduction of the coercive force. And with the increase of stress, reduce materialcoercivity force,so the coercivity force iron magnetic material is inversely proportional to thesize of stress. Therefore, coercivity force can detect the stress concentration area by themeasurement of ferromagnetic material.