本文選題：焊接變形預(yù)測 + 船體大型結(jié)構(gòu)件��； 參考：《江蘇科技大學(xué)》2016年碩士論文

【摘要】：船舶工業(yè)是為水上交通、海洋開發(fā)和國防建設(shè)等行業(yè)提供技術(shù)裝備的現(xiàn)代綜合性產(chǎn)業(yè)。大型船舶結(jié)構(gòu)件體積龐大,一次整體制造困難,國內(nèi)外的造船廠建造的大型船舶往往將其分成幾段或十幾段相對較小的結(jié)構(gòu)件分別焊接制造,最后再把各個分段拼裝焊接起來。焊接局部不均勻的加熱和冷卻使得船舶與海洋工程等重要結(jié)構(gòu)件產(chǎn)生各種焊接變形。結(jié)構(gòu)件的焊接變形不僅導(dǎo)致船體焊接和裝配的難度加大同時也會造成焊接精度問題,降低結(jié)構(gòu)的承載能力。所以在建造大型船舶的每個分段時需要研究焊接結(jié)構(gòu)件的殘余應(yīng)力和焊接變形問題。為了掌握焊接變形的規(guī)律,就應(yīng)對焊接溫度場及焊接過程中的應(yīng)力變形進行準確的分析。常用的焊接應(yīng)力變形數(shù)值模擬方法有熱彈塑性有限元法和固有應(yīng)變法,熱彈塑性計算是典型非線性過程(材料非線性、幾何非線性等),矩陣方程奇異性大,計算結(jié)果收斂困難需要多次迭代才能達到必要的精度,不適用于大型結(jié)構(gòu)件應(yīng)力變形預(yù)測,故本文采用固有應(yīng)變法預(yù)測大型結(jié)構(gòu)件應(yīng)力變形。針對大型船體結(jié)構(gòu)件(底板、縱骨和肋板焊接結(jié)構(gòu)),本文選取其中一個典型小結(jié)構(gòu)件(T型接頭雙邊開45°角V形坡口)進行熔化極氣體保護焊(MAG)焊接實驗,使用盲孔法對典型小結(jié)構(gòu)件(T型接頭)進行焊后殘余應(yīng)力實驗,并繪制出殘余應(yīng)力分布規(guī)律圖;建立典型小結(jié)構(gòu)(T型接頭)的數(shù)學(xué)模型,確定材料熱物性參數(shù)、邊界條件、熱源模型及約束條件等;使用ANSYS仿真軟件進行熱彈塑性有限元分析,計算小結(jié)構(gòu)的溫度場、應(yīng)力應(yīng)變、變形的分布;下一步采用固有應(yīng)變的有限元分析方法,將小結(jié)構(gòu)熱彈塑性有限元計算得到的固有變形轉(zhuǎn)化為固有應(yīng)變加載到大型結(jié)構(gòu)上,使用大型焊接變形仿真軟件預(yù)測大型船體結(jié)構(gòu)的焊接變形。研究結(jié)果表明:底板與縱骨八條長焊縫焊接后,整個結(jié)構(gòu)件的橫向收縮最大值為13.056mm,底板左下端和右上端橫向收縮較大。左側(cè)的三根縱骨向右側(cè)橫向收縮變形,右側(cè)的三根肋骨向左側(cè)橫向收縮變形,中間兩根縱骨橫向收縮量較小。整個結(jié)構(gòu)件縱向最大收縮量為16.9 mm且底板和縱骨上端的縱向收縮量較下端的大;底板與肋板、肋板與側(cè)板八條長焊縫焊接后,整個大結(jié)構(gòu)件產(chǎn)生縱向收縮,最大收縮量為19.28mm,底板和側(cè)板的兩端沿著長度方向向中間收縮變形,底板和肋板分別沿著各自的寬度方向發(fā)生橫向收縮,橫向收縮最大量為6.47mm。計算結(jié)果表明,基于固有應(yīng)變的有限元分析方法能夠比較合理地預(yù)測大型結(jié)構(gòu)件的焊接變形,使得大型結(jié)構(gòu)件焊接變形情況預(yù)測成為可能,對于實際焊接生產(chǎn)有一定的指導(dǎo)作用。
[Abstract]:Shipbuilding industry is a modern comprehensive industry which provides technical equipment for water transportation, marine development and national defense construction. Because of the large size of large ship structural parts, it is difficult to be manufactured at one time. Large ships built by shipyards at home and abroad are often welded into several sections or more than a dozen relatively small structural parts, and finally each segment is welded together. Welding local uneven heating and cooling cause various welding deformation of important structures such as ship and ocean engineering. The welding deformation of structural parts not only makes it more difficult to weld and assemble the hull, but also causes the welding precision problem and reduces the bearing capacity of the structure. So it is necessary to study the residual stress and welding deformation of welded structure when building each section of large ship. In order to master the rules of welding deformation, the welding temperature field and stress deformation in welding process should be analyzed accurately. The commonly used numerical simulation methods for welding stress and deformation are thermoelastic-plastic finite element method and inherent strain method. Thermoelastic-plastic calculation is a typical nonlinear process (material nonlinearity, geometric nonlinearity, etc.) The convergence of calculation results requires several iterations in order to achieve the necessary accuracy and is not suitable for the prediction of stress and deformation of large structural parts, so the inherent strain method is used to predict the stress and deformation of large structural parts in this paper. Aiming at large hull structure (bottom plate, longitudinal frame and ribbed plate welding structure), this paper selects one of typical small structure parts as T joint with 45 擄angle V groove to carry out gas shielded welding (MAG) welding experiment. Using blind hole method, the residual stress of typical small structure parts is tested after welding, and the distribution pattern of residual stress is drawn, the mathematical model of typical small structure T joint is established, and the material thermal physical parameters and boundary conditions are determined. The thermal source model and constraint conditions, ANSYS simulation software for thermoelastic-plastic finite element analysis, to calculate the temperature field, stress, strain, deformation distribution of small structures, the next step is to use the natural strain finite element analysis method, The thermal elastoplastic finite element analysis of small structures is transformed into inherent strain loading on large structures, and the welding deformation of large hull structures is predicted by large welding deformation simulation software. The results show that the maximum transverse shrinkage of the whole structure is 13.056mm after welding between the bottom plate and the longitudinal bone eight long welds, and the transverse shrinkage of the bottom plate at the left lower end and the right upper end is larger. The three longitudinal bones on the left contracted and deformed laterally to the right, the three ribs on the right contracted and deformed to the left, and the transverse contraction of the two longitudinal bones in the middle was relatively small. The maximum longitudinal shrinkage of the whole structure is 16.9 mm, and the longitudinal shrinkage of the bottom plate and the upper end of the longitudinal bone is greater than that of the lower end, and the longitudinal shrinkage of the whole large structure is produced after the welding of eight long welds between the bottom plate and the rib plate, the rib plate and the side plate. The maximum shrinkage is 19.28 mm. The two ends of the bottom plate and the side plate contract and deform along the length direction. The transverse shrinkage of the bottom plate and the ribbed plate is 6.47 mm. The calculation results show that the finite element analysis method based on inherent strain can reasonably predict the welding deformation of large structural parts, which makes it possible to predict the welding deformation of large structural parts. It has certain guiding function for actual welding production.
【學(xué)位授予單位】：江蘇科技大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2016
【分類號】：U671.83;TG404

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