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  本文關鍵詞： 焊接 數(shù)值模擬 殘余應力 殘余變形 溫度場 應力場 T型相貫節(jié)點　出處：《西南交通大學》2014年碩士論文　論文類型：學位論文

【摘要】：鋼結構以其剛度高、自重輕、易于施工、抗震性能好等優(yōu)點,一直是被廣泛采用的一種工程結構,近百年來得到了快速的發(fā)展。鋼管由于其結構簡單、抗疲勞、抗沖擊能力較強,也成為了工程師青睞的對象,隨著鋼管結構和鋼管—混凝土組合結構廣泛應用,也開始嘗試鋼管桁架拱橋。鋼管的連接普遍采用焊接,但由于焊接殘余應力的存在,可能會導致焊縫處結構性能的降低,譬如降低了結構的抗疲勞、抗應力腐蝕能力和穩(wěn)定性能等。同時焊接殘余變形也直接影響構件的加工精度,進而影響構件的受力穩(wěn)定性。因此對于重大得橋梁工程鋼結構,從經(jīng)濟、安全等方面考慮,對焊接結構的殘余應力和變形分布規(guī)律的準確認識和控制變得尤為重要。 首先,本文闡述了焊接殘余應力的概念和產生的原因及對焊接結構的影響,綜述了焊接殘余應力數(shù)值模擬技術的特點以及溫度場、應力場的研究歷史和發(fā)展。其次,對焊接的傳熱過程進行了理論分析,并介紹了溫度場和應力場有限元計算方法。然后,基于ANSYS對鋼管結構最常用的T型相貫節(jié)點的焊接溫度場和應力場進行了三維有限元數(shù)值模擬,對單元類型的選擇、網(wǎng)格尺寸的劃分、時間步長的選擇以及邊界條件的選取進行了研究。采用形狀規(guī)則的無中間節(jié)點的三維實體六面體單元,在近熱源區(qū)域采用極細網(wǎng)格,遠離熱源區(qū)域則采用稀疏網(wǎng)格,用相對局部坐標實現(xiàn)焊接熱源的加載,用單元生死技術實現(xiàn)焊縫金屬填充過程的模擬。采用雙橢球熱源模型模擬焊接熱源,并通過ANSYS參數(shù)化設計語言APDL編程實現(xiàn)了模擬熱源移動,得出了T型相貫節(jié)點的焊接溫度場、殘余應力及應變的分布規(guī)律,與經(jīng)典理論相符合。最后,通過參數(shù)變化法分析熱源參數(shù)、焊接速度以及焊縫寬度對焊接殘余應力和變形的影響,為焊接工藝改進和焊接結構優(yōu)化設計提供了重要依據(jù)。
[Abstract]:Due to its high stiffness, light weight, easy construction and good seismic performance, steel structure has been widely used as an engineering structure, and has been developed rapidly in the last hundred years. With the wide application of steel tube structure and steel-concrete composite structure, the steel tube truss arch bridge has been tried. However, due to the existence of welding residual stress, the structural properties of welding seam may be reduced, for example, the fatigue resistance, stress corrosion resistance and stability of the structure can be reduced. At the same time, the welding residual deformation also directly affects the machining accuracy of the components. Therefore, it is very important to understand and control the distribution law of residual stress and deformation of welded structures from the aspects of economy and safety. Firstly, the concept and cause of welding residual stress and its influence on welding structure are described. The characteristics of numerical simulation technology of welding residual stress and the history and development of temperature field and stress field are summarized. The heat transfer process of welding is analyzed theoretically, and the finite element calculation method of temperature field and stress field is introduced. Based on ANSYS, the temperature field and stress field of T-shaped intersecting joints are simulated by three-dimensional finite element method. The selection of element type and the division of mesh size are carried out. The selection of time step size and boundary conditions are studied. The hexahedron element with no intermediate nodes is used in the near heat source region and the sparse grid in the far away heat source region. The welding heat source is loaded with relative local coordinates, the process of weld metal filling is simulated by element birth and death technique, and the welding heat source is simulated by double ellipsoidal heat source model. The simulation of heat source movement is realized by ANSYS parametric design language APDL, and the distribution of welding temperature field, residual stress and strain of T-type intersecting joints is obtained, which is in accordance with the classical theory. The influence of heat source parameters, welding speed and weld width on welding residual stress and deformation is analyzed by parameter variation method, which provides an important basis for welding process improvement and welding structure optimization design.
【學位授予單位】：西南交通大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：U441;U445.583

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本文編號：1521103