【摘要】：隨著管道運輸?shù)膹V泛運用,隨之而來的管網(wǎng)安全問題值得關(guān)注。石油天然氣管道通常選用低碳鋼制作,隨著時間的積累,服役管道不可避免會出現(xiàn)疲勞失效,疲勞失效的部位通常出現(xiàn)在應(yīng)力集中區(qū)域。石油天然氣管道破損、斷裂會引發(fā)石油天然氣泄漏,嚴重時可發(fā)生爆炸。因此,對管道的應(yīng)力檢測方法進行研究,形成完善的應(yīng)力集中區(qū)域測量體系,是避免事故發(fā)生的重要手段。鐵磁性材料的磁性參數(shù)都會受到應(yīng)力的影響,其中矯頑力與應(yīng)力存在一定關(guān)系且測量不易受外界影響,可利用矯頑力間接測量應(yīng)力,對應(yīng)力集中區(qū)域檢測具有重要意義。本文主要研究了鐵磁性材料關(guān)于磁特性、磁效應(yīng)、磁化原理等一系列理論。為了驗證通過矯頑力間接測應(yīng)力的可行性,研究了應(yīng)力對鐵磁性材料矯頑力的影響:矯頑力是源于材料疇壁的不可逆磁化過程,而應(yīng)力的存在阻礙了不可逆磁化過程,因此影響了鐵磁性材料的矯頑力。實驗采用U型探頭進行測量,將多片U型硅鋼片疊加構(gòu)成探頭,并在上面均勻一定匝數(shù)的纏繞激勵線圈和感應(yīng)線圈,將探頭放置在被測工件上,忽略探頭與被測試的空氣間隙,構(gòu)成一個閉合回路。通入一定波形、一定頻率的激勵信號,探頭和被測試件被磁化,在閉合回路中產(chǎn)生變化的磁通量,感應(yīng)線圈中生成感應(yīng)電動勢。激勵端接入一個采樣電阻,采集與磁場強度成正比的電信號,此信號接入示波器1通道。感應(yīng)端接入積分電路,采集與磁感應(yīng)強度成正比的電信號,此信號接入示波器2通道。隨著激勵信號變化,在示波器上兩個信號輸出端構(gòu)成磁滯回線,磁滯回線上,磁感應(yīng)強度為零時對應(yīng)的磁場強度即為矯頑力。實驗中,依次選擇選用正弦比、三角波和方波作為激勵信號進行測量,當激勵信號為40Hz的方波時,測量效果較好。分別測量被測試件在不同外力作用狀態(tài)下以及不同厚度試件的磁滯回線變化情況,并計算對應(yīng)的矯頑力。實驗結(jié)果表明:鐵磁性材料所受到的應(yīng)力越大,其矯頑力越小,厚度對材料的矯頑力沒有影響。
[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.
【學(xué)位授予單位】：沈陽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：TM271

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相關(guān)期刊論文 前10條

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本文編號：2351561