本文關(guān)鍵詞： 正交異性鋼橋面板 殘余應(yīng)力 溫度場 應(yīng)力場 焊接 數(shù)值模擬　出處：《西南交通大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：正交異性鋼橋面板由于各方面具有的獨特優(yōu)勢,于現(xiàn)代橋梁建設(shè)中得到越來越廣泛地認可與使用。然而隨著服役時間的增加,許多橋面板上已經(jīng)涌現(xiàn)出不同程度的疲勞問題,對結(jié)構(gòu)的使用性和安全性造成了非常嚴重的影響。正交異性鋼橋面板結(jié)構(gòu)復(fù)雜,縱肋、橫肋等焊接到橋面板上,焊接所產(chǎn)生的殘余應(yīng)力以及應(yīng)力集中對疲勞強度有著極為不利的影響。本文針對此特殊構(gòu)造,模擬其焊接加工過程并計算焊后殘余應(yīng)力值,得出該結(jié)構(gòu)殘余應(yīng)力整體分布情況,重點關(guān)注極易出現(xiàn)裂紋處的焊接殘余應(yīng)力分布狀況。論文主要工作如下：首先,介紹了正交異性鋼橋面板及其由焊接引發(fā)的疲勞問題,再分別概括了焊接殘余應(yīng)力的定義、分類、產(chǎn)生的原因和對結(jié)構(gòu)的影響,總結(jié)歸納了有哪些實驗測試方法以及簡要敘述了它的消除方式,并結(jié)合實驗所用測試方法以及殘余應(yīng)力消除措施做了進一步說明。其次,有針對性地論述了有限元分析理論在焊接中的應(yīng)用及其特點,并總結(jié)了有限元模擬焊接過程涉及的關(guān)鍵技術(shù)。列出了焊接熱過程中傳熱基本形式、有限元方法分析的基本方程,進一步闡述了對于涉及非線性瞬態(tài)問題時,分析所用離散方法。同時,簡要說明了在有限元分析焊接應(yīng)力場時所用基本理論與準則。然后,對基于ANSYS軟件的熱分析方法進行概述。詳細總結(jié)了模擬焊接溫度場、應(yīng)力場的步驟及方法,其中待解決的關(guān)鍵問題有：模型的建立、網(wǎng)格的劃分、單元的選擇、熱源的選擇、邊界條件的確定、荷載的施加、溫度場與應(yīng)力場之間的耦合、模擬熱源的移動、焊縫逐步成形的關(guān)鍵技術(shù)以及荷載步的確定。最后,依據(jù)上述理論研究并參照實驗?zāi)Ｐ徒⒂嬎隳Ｐ�。確立采用三維有限元數(shù)值方法模擬其溫度場及應(yīng)力場,針對問題選取形狀規(guī)則的無中間節(jié)點的六面體實體單元以及一定溫度范圍內(nèi)的材料熱物理參數(shù),合理規(guī)劃網(wǎng)格劃分密度,邊界條件選擇室溫且結(jié)合實際情況確定采用雙橢球熱源模型,并對熱源參數(shù)的選取進行評定,采用參數(shù)化設(shè)計語言編寫程序?qū)崿F(xiàn)熱源移動；應(yīng)力場計算時,施加邊界條件限制剛體位移并讀入計算所得的溫度荷載,再利用生死單元法模擬焊縫的逐步填充。首先計算得到U肋焊于橋面板的溫度場和應(yīng)力場分布；在此基礎(chǔ)上拼裝橫隔板,繼而研究兩種不同橫隔板構(gòu)造下各自殘余應(yīng)力分布狀況,主要對兩種結(jié)果進行對比分析,綜合評判哪種構(gòu)造細節(jié)應(yīng)力分布對結(jié)構(gòu)整體疲勞強度更為有利；再對加焊橫隔板前后U肋焊縫殘余應(yīng)力分布變化做了簡單分析；最后用實驗所測數(shù)據(jù)對計算結(jié)果進行校核驗證計算值的可靠性,為優(yōu)化焊接結(jié)構(gòu)、選擇更合理的焊接形式提供重要依據(jù)。同時,本文數(shù)值模擬所得的殘余應(yīng)力大小和分布情況為今后評價結(jié)構(gòu)的疲勞強度做好了鋪墊。
[Abstract]:Due to the unique advantages of orthotropic steel bridge panels, they are more and more widely recognized and used in modern bridge construction. However, with the increase of service time, fatigue problems of various degrees have emerged on many deck panels. The structure of orthotropic steel bridge is complicated, longitudinal rib and transverse rib are welded to the deck of the bridge. The residual stress and stress concentration produced by welding have a very adverse effect on the fatigue strength. In this paper, the welding process of the structure is simulated and the residual stress value after welding is calculated, and the overall distribution of residual stress in the structure is obtained. The main work of this paper is as follows: firstly, this paper introduces orthotropic steel bridge face and fatigue caused by welding, and then generalizes the definition of welding residual stress. Classification, causes and effects on structures, summarizes and summarizes the experimental test methods and briefly describes its elimination methods, and further explains the test methods and residual stress relief measures used in the experiments. In this paper, the application and characteristics of finite element analysis theory in welding are discussed, and the key technologies involved in simulating welding process by finite element method are summarized. The basic forms of heat transfer in welding heat process and the basic equations of finite element method analysis are listed. The discrete method used in the analysis of nonlinear transient problems is further expounded. At the same time, the basic theory and criteria used in finite element analysis of welding stress field are briefly explained. The method of thermal analysis based on ANSYS software is summarized. The steps and methods of simulating welding temperature field and stress field are summarized in detail. The key problems to be solved are the establishment of model, the division of grid, the selection of element, the selection of heat source, and so on. The determination of boundary condition, the application of load, the coupling of temperature field and stress field, the movement of simulated heat source, the key technology of weld forming step by step and the determination of load step. According to the above theoretical research and referring to the experimental model, the calculation model is established. The three-dimensional finite element numerical method is used to simulate the temperature field and stress field. In order to solve the problem, the hexahedron solid element without intermediate node and the material thermophysical parameters in a certain temperature range are selected, and the density of mesh is reasonably planned. The boundary conditions are chosen at room temperature and combined with the actual conditions. The double ellipsoid heat source model is adopted, and the selection of the heat source parameters is evaluated. The program is written by parametric design language to realize the heat source movement. When the stress field is calculated, The boundary condition is applied to limit the rigid body displacement and read the calculated temperature load. Then the progressive filling of the weld is simulated by the birth and death element method. Firstly, the distribution of temperature field and stress field of the U-rib welding on the bridge slab is calculated. On this basis, the transverse diaphragm is assembled, and then the distribution of residual stress under two different structures is studied, and the two results are compared and analyzed. The variation of residual stress distribution of U-ribbed weld before and after welding is analyzed simply by synthetically judging which structural detail stress distribution is more favorable to the overall fatigue strength of the structure. Finally, the reliability of the calculated results is verified by the experimental data, which provides an important basis for optimizing the welding structure and selecting a more reasonable welding form. The magnitude and distribution of residual stress obtained by numerical simulation in this paper provide a good basis for evaluating the fatigue strength of structures in the future.
【學(xué)位授予單位】：西南交通大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：U441.4;U445.7

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