铁磁性材料矫顽力测应力系统的测量技术研究
发布时间：2018-11-23 12:09
【摘要】：随着管道运输的广泛运用,随之而来的管网安全问题值得关注。石油天然气管道通常选用低碳钢制作,随着时间的积累,服役管道不可避免会出现疲劳失效,疲劳失效的部位通常出现在应力集中区域。石油天然气管道破损、断裂会引发石油天然气泄漏,严重时可发生爆炸。因此,对管道的应力检测方法进行研究,形成完善的应力集中区域测量体系,是避免事故发生的重要手段。铁磁性材料的磁性参数都会受到应力的影响,其中矫顽力与应力存在一定关系且测量不易受外界影响,可利用矫顽力间接测量应力,对应力集中区域检测具有重要意义。本文主要研究了铁磁性材料关于磁特性、磁效应、磁化原理等一系列理论。为了验证通过矫顽力间接测应力的可行性,研究了应力对铁磁性材料矫顽力的影响:矫顽力是源于材料畴壁的不可逆磁化过程,而应力的存在阻碍了不可逆磁化过程,因此影响了铁磁性材料的矫顽力。实验采用U型探头进行测量,将多片U型硅钢片叠加构成探头,并在上面均匀一定匝数的缠绕激励线圈和感应线圈,将探头放置在被测工件上,忽略探头与被测试的空气间隙,构成一个闭合回路。通入一定波形、一定频率的激励信号,探头和被测试件被磁化,在闭合回路中产生变化的磁通量,感应线圈中生成感应电动势。激励端接入一个采样电阻,采集与磁场强度成正比的电信号,此信号接入示波器1通道。感应端接入积分电路,采集与磁感应强度成正比的电信号,此信号接入示波器2通道。随着激励信号变化,在示波器上两个信号输出端构成磁滞回线,磁滞回线上,磁感应强度为零时对应的磁场强度即为矫顽力。实验中,依次选择选用正弦比、三角波和方波作为激励信号进行测量,当激励信号为40Hz的方波时,测量效果较好。分别测量被测试件在不同外力作用状态下以及不同厚度试件的磁滞回线变化情况,并计算对应的矫顽力。实验结果表明:铁磁性材料所受到的应力越大,其矫顽力越小,厚度对材料的矫顽力没有影响。
[Abstract]:With the wide application of pipeline transportation, the problems of pipe network safety are worthy of attention. Oil and gas pipelines are usually made of low carbon steel. With the accumulation of time, fatigue failure will inevitably occur in the service pipeline, and the fatigue failure usually occurs in the stress concentration region. If the oil and gas pipeline is damaged and broken, it will cause oil and gas leakage, which can explode when serious. Therefore, it is an important means to avoid accidents by studying the stress detection method of pipeline and forming a perfect measuring system of stress concentration area. The magnetic parameters of ferromagnetic materials are all affected by stress, among which coercivity and stress are related to each other, and the measurement is not easy to be affected by the outside world. Therefore, the coercivity can be used to measure the stress indirectly, which is of great significance to the detection of stress concentration region. In this paper, a series of theories about magnetic properties, magnetic effects and magnetization principles of ferromagnetic materials are studied. In order to verify the feasibility of indirectly measuring stress by coercivity, the effect of stress on coercivity of ferromagnetic materials is studied. The coercivity comes from the irreversible magnetization process of the domain wall of the material, and the existence of the stress hinders the irreversible magnetization process. Therefore, the coercivity of ferromagnetic materials is affected. In the experiment, the U-shaped probe is used to measure, and the multi-piece U-shaped silicon steel sheet is superimposed to form the probe, and the winding excitation coil and induction coil with a certain number of turns are evenly distributed on the top. The probe is placed on the workpiece under test, and the air gap between the probe and the tested piece is ignored. Form a closed loop. The magnetic flux is changed in the closed loop and inductive electromotive force is generated in the inductive coil by magnetizing the excitation signal of a certain waveform and a certain frequency, the probe and the tested piece are magnetized. An electrical signal proportional to the magnetic field intensity is collected from the excitation end, which is connected to the oscilloscope 1 channel. The inductive end is connected to the integral circuit, and the signal is directly proportional to the magnetic induction intensity. The signal is connected to the 2 channels of oscilloscope. With the change of the excitation signal, the hysteresis loop is formed at the output of two signals on the oscilloscope, and the magnetic field intensity corresponding to 00:00 is the coercivity on the hysteresis loop. In the experiment, sinusoidal ratio, triangle wave and square wave are selected as excitation signals in turn. When the excitation signal is square wave of 40Hz, the measurement effect is better. The hysteresis loops of the tested specimens under different external forces and different thickness were measured, and the corresponding coercivity was calculated. The experimental results show that the greater the stress is, the smaller the coercivity of ferromagnetic materials is, and the thickness has no effect on the coercivity of ferromagnetic materials.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM271
[Abstract]:With the wide application of pipeline transportation, the problems of pipe network safety are worthy of attention. Oil and gas pipelines are usually made of low carbon steel. With the accumulation of time, fatigue failure will inevitably occur in the service pipeline, and the fatigue failure usually occurs in the stress concentration region. If the oil and gas pipeline is damaged and broken, it will cause oil and gas leakage, which can explode when serious. Therefore, it is an important means to avoid accidents by studying the stress detection method of pipeline and forming a perfect measuring system of stress concentration area. The magnetic parameters of ferromagnetic materials are all affected by stress, among which coercivity and stress are related to each other, and the measurement is not easy to be affected by the outside world. Therefore, the coercivity can be used to measure the stress indirectly, which is of great significance to the detection of stress concentration region. In this paper, a series of theories about magnetic properties, magnetic effects and magnetization principles of ferromagnetic materials are studied. In order to verify the feasibility of indirectly measuring stress by coercivity, the effect of stress on coercivity of ferromagnetic materials is studied. The coercivity comes from the irreversible magnetization process of the domain wall of the material, and the existence of the stress hinders the irreversible magnetization process. Therefore, the coercivity of ferromagnetic materials is affected. In the experiment, the U-shaped probe is used to measure, and the multi-piece U-shaped silicon steel sheet is superimposed to form the probe, and the winding excitation coil and induction coil with a certain number of turns are evenly distributed on the top. The probe is placed on the workpiece under test, and the air gap between the probe and the tested piece is ignored. Form a closed loop. The magnetic flux is changed in the closed loop and inductive electromotive force is generated in the inductive coil by magnetizing the excitation signal of a certain waveform and a certain frequency, the probe and the tested piece are magnetized. An electrical signal proportional to the magnetic field intensity is collected from the excitation end, which is connected to the oscilloscope 1 channel. The inductive end is connected to the integral circuit, and the signal is directly proportional to the magnetic induction intensity. The signal is connected to the 2 channels of oscilloscope. With the change of the excitation signal, the hysteresis loop is formed at the output of two signals on the oscilloscope, and the magnetic field intensity corresponding to 00:00 is the coercivity on the hysteresis loop. In the experiment, sinusoidal ratio, triangle wave and square wave are selected as excitation signals in turn. When the excitation signal is square wave of 40Hz, the measurement effect is better. The hysteresis loops of the tested specimens under different external forces and different thickness were measured, and the corresponding coercivity was calculated. The experimental results show that the greater the stress is, the smaller the coercivity of ferromagnetic materials is, and the thickness has no effect on the coercivity of ferromagnetic materials.
【学位授予单位】：沈阳工业大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TM271
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相关期刊论文 前10条
1 高铭;王平;黄凯;许建芹;吴杰;;基于巴克豪森原理的Q235钢沿深度方向应力分布检测[J];无损检测;2015年11期
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