超厚板箱体结构焊接温度场及应力场的三维数值模拟

发布时间：2018-04-15 13:32

本文选题：超厚板 + 残余应力　；参考：《武汉理工大学》2013年硕士论文

【摘要】：焊接技术发源于机械加工行业,是一种高效经济的材料加工手段。随着建筑钢结构的普及,焊接技术也逐渐应用到土木结构领域。近几年,大型钢结构层出不穷,结构高度也不断增加,与之相适应的是钢板厚度不断增加,钢构尺寸不断增大。在焊接拼装过程中,超厚板、超大尺寸钢结构容易产生焊接残余应力及变形等问题,进而影响构件安装的精度和施工质量。在构件的焊接拼装之前,通过计算机模拟焊接中的温度场和应力场,提前预测焊接温度的变化及应力和变形情况,具有快捷和经济的优点,也可以为现场施工提供指导,提高工作效率,降低施工成本,因此具有重要的现实意义。本文从焊接热传导的基础理论出发,以有限元分析方法为手段,对80mm超厚板的焊接热循环过程及超大型超厚板箱体钢结构的焊接过程进行动态模拟,同时计算出焊接温度和残余应力应变的分布情况。针对厚板或超厚板的焊接,本文提出如下新思维：选择双椭球热源模型和必要的简化手段来模拟超厚板的焊接过程具有模拟的可行性和结果的可靠性；利用ANSYS的参数化设计语言程序可以实现多条焊缝同时施焊的模拟过程。在钢结构的设计阶段,考虑到焊接安装的质量要求,设计人员可以事先通过计算机模拟来选择最佳的焊接顺序,以满足施工的质量要求；通过箱体结构的焊接模拟,我们可以得知其边缘区域(与后续焊接工作相接合的部位)的温度基本维持在室温,且此区域的焊接残余应力很小,不会发生屈服现象。虽然边缘区域的变形受到焊缝区域塑性变形累积效应的影响,但在整体焊接过程中模型与其它构件相连焊接点的最大位移为O.08mm左右,这个数据在现场施工的可控范围内。同时,本文针对同一厚度的超厚板多道焊的焊接过程作温度场模拟,通过比较焊接温度的变化幅度,得出：增加焊道数目,可以提高焊接质量,即多道焊优于双道焊或单道焊；温度分布仅仅影响到与焊缝相连的钢板区域。同时本文也考虑了CO2焊所用焊丝与被焊钢板的热物理和力学性能参数随着温度而变化的因素,这样既符合实际情况,又不影响计算结果的可靠性。
[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.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU391

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