本文選題：超厚板 + 殘余應(yīng)力　； 參考：《武漢理工大學(xué)》2013年碩士論文

【摘要】：焊接技術(shù)發(fā)源于機械加工行業(yè),是一種高效經(jīng)濟的材料加工手段。隨著建筑鋼結(jié)構(gòu)的普及,焊接技術(shù)也逐漸應(yīng)用到土木結(jié)構(gòu)領(lǐng)域。近幾年,大型鋼結(jié)構(gòu)層出不窮,結(jié)構(gòu)高度也不斷增加,與之相適應(yīng)的是鋼板厚度不斷增加,鋼構(gòu)尺寸不斷增大。在焊接拼裝過程中,超厚板、超大尺寸鋼結(jié)構(gòu)容易產(chǎn)生焊接殘余應(yīng)力及變形等問題,進而影響構(gòu)件安裝的精度和施工質(zhì)量。在構(gòu)件的焊接拼裝之前,通過計算機模擬焊接中的溫度場和應(yīng)力場,提前預(yù)測焊接溫度的變化及應(yīng)力和變形情況,具有快捷和經(jīng)濟的優(yōu)點,也可以為現(xiàn)場施工提供指導(dǎo),提高工作效率,降低施工成本,因此具有重要的現(xiàn)實意義。 本文從焊接熱傳導(dǎo)的基礎(chǔ)理論出發(fā),以有限元分析方法為手段,對80mm超厚板的焊接熱循環(huán)過程及超大型超厚板箱體鋼結(jié)構(gòu)的焊接過程進行動態(tài)模擬,同時計算出焊接溫度和殘余應(yīng)力應(yīng)變的分布情況。針對厚板或超厚板的焊接,本文提出如下新思維：選擇雙橢球熱源模型和必要的簡化手段來模擬超厚板的焊接過程具有模擬的可行性和結(jié)果的可靠性；利用ANSYS的參數(shù)化設(shè)計語言程序可以實現(xiàn)多條焊縫同時施焊的模擬過程。在鋼結(jié)構(gòu)的設(shè)計階段,考慮到焊接安裝的質(zhì)量要求,設(shè)計人員可以事先通過計算機模擬來選擇最佳的焊接順序,以滿足施工的質(zhì)量要求；通過箱體結(jié)構(gòu)的焊接模擬,我們可以得知其邊緣區(qū)域(與后續(xù)焊接工作相接合的部位)的溫度基本維持在室溫,且此區(qū)域的焊接殘余應(yīng)力很小,不會發(fā)生屈服現(xiàn)象。雖然邊緣區(qū)域的變形受到焊縫區(qū)域塑性變形累積效應(yīng)的影響,但在整體焊接過程中模型與其它構(gòu)件相連焊接點的最大位移為O.08mm左右,這個數(shù)據(jù)在現(xiàn)場施工的可控范圍內(nèi)。 同時,本文針對同一厚度的超厚板多道焊的焊接過程作溫度場模擬,通過比較焊接溫度的變化幅度,得出：增加焊道數(shù)目,可以提高焊接質(zhì)量,即多道焊優(yōu)于雙道焊或單道焊；溫度分布僅僅影響到與焊縫相連的鋼板區(qū)域。同時本文也考慮了CO2焊所用焊絲與被焊鋼板的熱物理和力學(xué)性能參數(shù)隨著溫度而變化的因素,這樣既符合實際情況,又不影響計算結(jié)果的可靠性。
[Abstract]:Welding technology originated in the mechanical processing industry, is an efficient and economical means of material processing.With the popularization of building steel structure, welding technology is gradually applied to the field of civil structure.In recent years, large steel structures have emerged in endlessly, and the height of the structures has been increasing. The thickness of steel plates and the size of steel structures have been increasing.In the process of welding and assembling, the problems of welding residual stress and deformation are easy to occur in the super-thick plate and super-large steel structure, which will affect the installation accuracy and construction quality of the components.Before the component is welded and assembled, the temperature field and stress field in welding are simulated by computer, and the variation of welding temperature and stress and deformation are predicted in advance, which has the advantages of quick and economical, and can also provide guidance for field construction.It is of great practical significance to improve working efficiency and reduce construction cost.Based on the basic theory of welding heat conduction and the finite element analysis method, this paper simulates the welding heat cycle process of 80mm ultra-thick plate and the welding process of super-thick box steel structure by means of finite element analysis.At the same time, the distribution of welding temperature and residual stress and strain are calculated.For the welding of thick or ultra-thick plates, the following new ideas are put forward: selecting double ellipsoid heat source model and necessary simplified means to simulate the welding process of ultra-thick plates has the feasibility of simulation and reliability of the results;The simulation process of simultaneous welding of multiple welds can be realized by using the parametric design language of ANSYS.In the design stage of steel structure, considering the quality requirement of welding installation, the designer can select the best welding sequence through computer simulation in order to meet the quality requirement of construction, and through the welding simulation of box structure,It can be seen that the temperature of the edge region (where the welding work is joined with the subsequent welding work) is maintained at room temperature, and the welding residual stress in this region is very small, and there is no yield phenomenon.Although the deformation in the edge region is affected by the cumulative plastic deformation effect in the weld zone, the maximum displacement of the welding joint connected with other components in the whole welding process is about O.08mm, which is within the controllable range of site construction.At the same time, this paper simulates the temperature field of the multi-pass welding process of super-thick plate with the same thickness. By comparing the variation of welding temperature, it is concluded that increasing the number of welding passes can improve the welding quality, that is, multi-pass welding is better than double-pass welding or single-pass welding;The temperature distribution only affects the area of the steel plate connected to the weld.At the same time, the factors that the thermal physical and mechanical properties of wire and welded steel plate used in CO2 welding vary with temperature are considered, which is not only in line with the actual situation, but also does not affect the reliability of the calculation results.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2013
【分類號】：TU391

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