钢管拱桥T型相贯节点焊接残余应力数值模拟分析

发布时间：2018-02-21 05:15

本文关键词： 焊接数值模拟残余应力残余变形温度场应力场 T型相贯节点　出处：《西南交通大学》2014年硕士论文　论文类型：学位论文

【摘要】：钢结构以其刚度高、自重轻、易于施工、抗震性能好等优点,一直是被广泛采用的一种工程结构,近百年来得到了快速的发展。钢管由于其结构简单、抗疲劳、抗冲击能力较强,也成为了工程师青睐的对象,随着钢管结构和钢管—混凝土组合结构广泛应用,也开始尝试钢管桁架拱桥。钢管的连接普遍采用焊接,但由于焊接残余应力的存在,可能会导致焊缝处结构性能的降低,譬如降低了结构的抗疲劳、抗应力腐蚀能力和稳定性能等。同时焊接残余变形也直接影响构件的加工精度,进而影响构件的受力稳定性。因此对于重大得桥梁工程钢结构,从经济、安全等方面考虑,对焊接结构的残余应力和变形分布规律的准确认识和控制变得尤为重要。首先,本文阐述了焊接残余应力的概念和产生的原因及对焊接结构的影响,综述了焊接残余应力数值模拟技术的特点以及温度场、应力场的研究历史和发展。其次,对焊接的传热过程进行了理论分析,并介绍了温度场和应力场有限元计算方法。然后,基于ANSYS对钢管结构最常用的T型相贯节点的焊接温度场和应力场进行了三维有限元数值模拟,对单元类型的选择、网格尺寸的划分、时间步长的选择以及边界条件的选取进行了研究。采用形状规则的无中间节点的三维实体六面体单元,在近热源区域采用极细网格,远离热源区域则采用稀疏网格,用相对局部坐标实现焊接热源的加载,用单元生死技术实现焊缝金属填充过程的模拟。采用双椭球热源模型模拟焊接热源,并通过ANSYS参数化设计语言APDL编程实现了模拟热源移动,得出了T型相贯节点的焊接温度场、残余应力及应变的分布规律,与经典理论相符合。最后,通过参数变化法分析热源参数、焊接速度以及焊缝宽度对焊接残余应力和变形的影响,为焊接工艺改进和焊接结构优化设计提供了重要依据。
[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.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U441;U445.583

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