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電磁脹環(huán)高速變形過程多物理場耦合分析及其測量技術(shù)研究

發(fā)布時間:2018-09-13 13:30
【摘要】:電磁成形技術(shù)是目前突破傳統(tǒng)輕質(zhì)鋁合金成形制造工藝缺陷的極具潛力的技術(shù)之一。但是,電磁成形過程是一個由電磁場、結(jié)構(gòu)場、溫度場等多物理場耦合作用下的物理過程,其成形過程復(fù)雜,材料在多場作用下,其變形性能也得到改變,其成形機理十分復(fù)雜。而電磁脹環(huán)是一種可視為處于環(huán)向單向拉伸狀態(tài)的電磁成形過程,其結(jié)構(gòu)高度對稱,各物理場分布均勻,分析難度較小。因此,本研究基于電磁脹環(huán)實驗,對電磁脹環(huán)過程當(dāng)中各物理場的相互耦合進行分析,并建立電磁脹環(huán)有限元仿真模型,對電磁脹環(huán)過程當(dāng)中的關(guān)鍵物理量——金屬環(huán)工件渦流、金屬環(huán)工件高速變形的徑向位移搭建測量系統(tǒng)并進行測量。本文選用電磁脹環(huán)作為研究模型,對電磁成形過程中,電磁場、結(jié)構(gòu)場、溫度場等多物理場的耦合作用進行了分析。對電磁脹環(huán)實驗平臺的驅(qū)動電路進行了建模,對成形線圈和金屬環(huán)工件的電磁過程進行了分析,對金屬環(huán)工件的受力過程和運動狀態(tài)進行了簡化分析,對電磁成形過程的熱能來源以及溫度變化對材料的影響進行了探討。然后利用COMSOL Multiphysics多物理場建模與仿真軟件對電磁脹環(huán)模型進行了2D軸對稱建模,對電磁脹環(huán)過程進行了數(shù)值模擬分析。在電磁脹環(huán)過程中,由于成形線圈中的電流變化而在金屬環(huán)工件中產(chǎn)生了感應(yīng)電流,從而使得金屬環(huán)工件受到了相應(yīng)的電磁力作用。對該感應(yīng)電流的測量對于分析金屬環(huán)工件在高速變形中的受力和應(yīng)力應(yīng)變十分重要。由于任何物理接觸都會對金屬環(huán)工件中感應(yīng)電流的產(chǎn)生影響,而羅科線圈又是一種良好的非接觸式電流傳感器,因此,本文提出了一種基于羅科線圈的間接測量法對金屬環(huán)工件中的感應(yīng)電流進行測量,并分析了其測量原理,設(shè)計了一套基于該原理的的渦流測量系統(tǒng),使用間接測量法所需要的羅科線圈進行了電磁脹環(huán)渦流測量實驗,并將實驗結(jié)果與有限元仿真結(jié)果進行了對比。針對電磁成形過程中,金屬工件高速變形行為研究中的位移測量難題,本文提出了一種基于電磁探針的電磁脹環(huán)高速位移測量方法,并分析了其測量原理,設(shè)計了一套基于電磁探針的高速位移測量系統(tǒng)。通過測量金屬環(huán)工件中的感應(yīng)渦流在電磁探針中產(chǎn)生的磁通量,獲得了金屬環(huán)工件感應(yīng)渦流的磁場分布。利用金屬環(huán)工件在膨脹過程中,當(dāng)工件通過同軸心分布的電磁探針時,其相應(yīng)電磁探針中磁通量為零的特點,搭建了有多個電磁探針的測量板,測量得到了金屬環(huán)工件的實時位移曲線,并同時使用了高速攝像機測量以驗證該方案的有效性,結(jié)果得出兩者測量結(jié)果趨于一致。該高速位移測量方案為電磁成形過程中金屬工件高速變形行為的研究提供了一種有效、簡潔的測量手段。
[Abstract]:Electromagnetic forming technology is one of the most potential technologies to break through the defects of traditional light aluminum alloy forming process. However, the electromagnetic forming process is a physical process under the coupling of electromagnetic field, structure field, temperature field and other physical fields. The forming process is complex, and the deformation property of the material is changed under the action of many fields. The forming mechanism is very complex. The electromagnetic expansion ring is a kind of electromagnetic forming process which can be regarded as being in the state of circumferential uniaxial tension. Its structure is highly symmetrical, the distribution of physical fields is uniform, and it is less difficult to analyze. Therefore, based on the experiment of electromagnetic expansion ring, the coupling of each physical field in the process of electromagnetic expansion is analyzed, and the finite element simulation model of electromagnetic expansion ring is established. The measurement system for the radial displacement of the metal ring workpiece and the metal ring workpiece with high speed deformation is built and measured, which is the key physical quantity in the process of electromagnetic expansion. In this paper, the coupling of electromagnetic field, structure field, temperature field and other multi-physical fields in electromagnetic forming process is analyzed by using the electromagnetic expansion ring as the research model. The driving circuit of the electromagnetic expansion ring experimental platform is modeled, the electromagnetic process of the forming coil and the metal ring workpiece is analyzed, and the stress process and motion state of the metal ring workpiece are simplified. The source of heat energy in electromagnetic forming process and the influence of temperature change on material are discussed. Then the 2D axisymmetric model of the electromagnetic expansion ring model is modeled by using COMSOL Multiphysics multi-physical field modeling and simulation software, and the numerical simulation of the electromagnetic expansion ring process is carried out. In the process of electromagnetic expansion the inductive current is produced in the metal ring workpiece because of the change of the current in the forming coil which makes the metal ring workpiece subjected to the corresponding electromagnetic force. The measurement of the inductive current is very important to analyze the stress and strain of metal ring workpiece in high speed deformation. Because any physical contact affects the inductive current in the metal ring workpiece and the Rocco coil is a good non-contact current sensor, In this paper, an indirect measurement method based on Rocco coil is proposed to measure the inductive current in metal ring workpiece, and its measuring principle is analyzed, and a eddy current measuring system based on this principle is designed. The eddy current measurement experiment of electromagnetic expansion ring is carried out by using the Rocco coil, which is needed by indirect measurement method, and the experimental results are compared with the results of finite element simulation. In view of the difficult problem of measuring the high speed deformation behavior of metal workpiece during electromagnetic forming, this paper presents a method of measuring high speed displacement of electromagnetic expansion ring based on electromagnetic probe, and analyzes its measuring principle. A high speed displacement measurement system based on electromagnetic probe is designed. By measuring the magnetic flux of the induced eddy current in the metal ring workpiece in the electromagnetic probe, the magnetic field distribution of the induced eddy current in the metal ring workpiece is obtained. Taking advantage of the fact that the magnetic flux of the metal ring workpiece is zero in the process of expansion, when the workpiece passes through the coaxial electromagnetic probe, a measuring plate with multiple electromagnetic probes is built. The real-time displacement curve of metal ring workpiece is obtained, and the high speed camera measurement is used to verify the effectiveness of the scheme. The results show that the two measurements tend to be consistent. The high speed displacement measurement scheme provides an effective and simple method for the study of high speed deformation behavior of metal workpieces during electromagnetic forming.
【學(xué)位授予單位】:華中科技大學(xué)
【學(xué)位級別】:碩士
【學(xué)位授予年份】:2015
【分類號】:TG391

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