電磁控制焊接溫度場的數(shù)值模擬研究（本科畢業(yè)論文設(shè)計）
摘 要

磁控焊接技術(shù)可以通過控制焊接接頭內(nèi)部的晶粒形態(tài)及其尺寸來獲得良好的接頭質(zhì)量，它是近年完善起來的一種新的焊接技術(shù)，在航空、航天冶金、機械等部門具有廣泛的應(yīng)用前景和巨大的實用價值。磁控焊接是一個涉及電弧物理、傳熱、冶金和力學(xué)的復(fù)雜過程。焊接現(xiàn)象包括焊接時的電磁、傳熱過程、金屬的熔化和凝固、冷卻時的相變、焊接應(yīng)力和變形等。一旦能夠?qū)崿F(xiàn)對各種焊接現(xiàn)象的計算機模擬，就可以在較短的時間內(nèi)通過模擬確定焊接結(jié)構(gòu)和材料的最佳設(shè)計、最佳工藝方法和焊接參數(shù)，從而可以保證焊接接頭質(zhì)量。
本文通過數(shù)值和物理實驗分析不同參數(shù)值時的焊接高斯分布模型，確定能夠合理表述磁控焊接電弧的模型和參數(shù)，通過ANSYS軟件對外加磁場作用下平板堆焊熔敷過程進(jìn)行三維動態(tài)模擬。分析模擬所得溫度場和應(yīng)力場，比較不同焊接工藝參數(shù)下的溫度場，同時對焊接溫度場實測結(jié)果與模擬結(jié)果進(jìn)行比較。研究表明：采用本文所提出的簡單磁控焊接電弧模型在一定范圍內(nèi)能夠較有效地對外加縱向磁場作用下平板堆焊熔敷過程進(jìn)行模擬，其結(jié)果與實測結(jié)果基本吻合。
利用本文提出的模擬分析方法，可以對磁控堆焊熔敷熱應(yīng)力與殘余應(yīng)力進(jìn)行預(yù)測。同時為優(yōu)化焊接結(jié)構(gòu)設(shè)計和焊接規(guī)范參數(shù)提供了理論依據(jù)和指導(dǎo)，促進(jìn)了有限元分析技術(shù)在堆焊熔敷過程中的應(yīng)用。


關(guān)鍵詞：縱向磁場，數(shù)值模擬，溫度場，應(yīng)力場

ABSTRACT

The technology of welding under external magnetic field is a new welding technology improving in recent years, which have a widely application prospect and great practical value in aviation, aerospace, metallurgy, machinery and other departments, which could obtain good welding quality by controlling the internal grain shape and size of welded joints. Welding under external magnetic field is a complicated physicochemical process which involves in electromagnetism, heat transferring, metal melting and freezing, phase-change, welding stress and deformation and so on. Once the complicated physicochemical process of welding can be achieved in the computer simulation, it can determine the best design, best technique and welding parameters of welding structures and materials by the computer simulation in a short period of time, thus guarantee the quality of welded joints.
In this paper, the models of Gaussian distribution with different value of the standard deviation of Gaussian distribution are compared and analyzed by the numerical and physical experiment, a simple model with reasonable parameters of EMS welding surface deposit is built up. Using ANSYS, three-dimensional finite element numerical simulation of plate surface deposit welding is carried out. The simulate results are analyzed, and then compared the temperature field with different welding parameters, compared the temperature field of measure and simulation. The study shows that the model can simulate the plate surface deposit welding process under external longitudinal magnetic field effectively in a certain range, and the simulation results agree with the measured results.
The thermal stress and residual stress in the plate surface deposit welding process can be predicted by using the simulative analysis method in this paper. It is also provides a theoretical basis and guidance to optimizing the welding structure design and parameters, promotes the application of Finite Element Method on welding engineering.


Key words: Longitudinal magnetic field, Numerical Simulation, Temperature field, Stress field

目 錄

中文摘要 Ⅰ
ABSTRACT Ⅱ
1緒論 1
1.1課題背景及研究意義 1
1.2國內(nèi)外研究現(xiàn)狀和發(fā)展趨勢 2
1.2.1焊接溫度場的研究現(xiàn)狀和發(fā)展趨勢 2
1.2.2焊接應(yīng)力場的研究現(xiàn)狀和發(fā)展趨勢 3
1.3研究的可行性 5
1.4課題主要研究內(nèi)容 6
2 焊接過程有限元理論基礎(chǔ) 7
2.1焊接過程有限元分析特點 7
2.2焊接溫度場的分析理論 7
2.3焊接應(yīng)力和應(yīng)變的分析理論 8
2.4 ANSYS軟件的介紹 9
2.4.1ANSYS軟件的特點 9
2.4.2ANSYS軟件的結(jié)構(gòu) 9
3外加磁場作用下平板熔敷堆焊溫度場數(shù)值模擬分析 11
3.1磁控焊接電弧模型的建立 11
3.2前處理 11
3.2.1建模 11
3.2.2材料特性參數(shù) 12
3.2.3確定單元類型和網(wǎng)格劃分 13
3.3載荷施加和求解 14
3.3.1時間步長的確定 14
3.3.2邊界條件處理 14
3.3.3熱源模型的確定 15
3.3.4移動熱源的加載及求解命令流 15
3.4溫度場后處理 16
3.4.1焊接溫度場的分布云圖 16
3.4.2不同焊接工藝參數(shù)下的溫度場分布云圖的比較 17
3.4.3焊接過程中的溫度曲線分析 21
3.5結(jié)果驗證 22
4外加磁場作用下平板熔敷堆焊應(yīng)力場的數(shù)值模擬分析 26
4.1焊接應(yīng)力場的計算方法 26
4.2焊接過程動態(tài)應(yīng)力應(yīng)變的分析 26
4.2.1焊接過程中應(yīng)力場分布云圖 26
4.2.2焊接過程中的應(yīng)力曲線分析 28
5結(jié)論 31
6展望 32
致謝 33
參考文獻(xiàn) 34