钢桥焊接细节残余应力分析及疲劳性能评估
发布时间：2018-08-04 11:25
【摘要】：伴随着我国桥梁建设的发展,钢结构桥梁的比重在不断的增大,出现了大量的焊接细节。我国焊接疲劳设计起步相对较晚,没有完善的焊接细节的疲劳设计标准。若对结构焊接细节设计不当,会出现钢桥焊接细节的疲劳裂纹,甚至造成严重的事故。 焊接是一个涉及物理、化学、力学的复杂过程,焊接加热冷却之后结构内部会存在复杂的残余应力。焊接节点传力过程中的应力集中,焊接节点焊接过程引起的初始缺陷及使结构呈现受拉状态的焊接残余应力是导致焊接节点疲劳性能显著降低的直接原因。反复荷载作用下,为准确描述焊接节点实际应力场状态,需要首先对焊接残余应力进行数值模拟,再叠加不同荷载幅引起的结构工作应力幅。焊接残余应力的准确模拟对焊接节点疲劳性能研究具有重要意义。 本文利用ANSYS程序对对接、T字形、U肋与顶板三种典型焊接细节的焊接残余应力进行了数值模拟,并对焊接接头危险点位进行了疲劳性能的分析,论文工作有以下几方面： 1根据高温条件下Q345的物理和力学参数,确定焊接热源模型、焊接过程的参数,实现了焊缝热源的移动加载,得出了三种接头准确的焊接过程温度场。编写了不同焊接接头焊接过程数值模拟的APDL命令。 2通过温度场和应力场的间接耦合调用三种接头温度场的计算结果,计算出残余应力的分布。对于U肋与顶板接头,等效残余应力随顶板厚度的增加而增加,起弧和灭弧的局部,残余应力略高于屈服强度。 3根据欧洲规范中三种接头名义应力加载计算出三种接头的实际应力,并选取应力集中较为严重的部位作为危险点。通过该点计算所得的残余应力与实际应力的叠加,采用Goodman关系结合Q345的材料S-N曲线绘制危险点的新S-N曲线。将计算结果与欧洲规范的焊接接头S-N曲线对比,分析了曲线差异的原因并提出了两个应力修正系数。
[Abstract]:With the development of the bridge construction in China, the proportion of the steel structure and bridge is increasing, and a lot of welding details have appeared. The welding fatigue design in our country is relatively late, and there is no perfect standard of fatigue design for welding details. A heavy accident.
Welding is a complex process involving physics, chemistry and mechanics. After the welding is heated and cooled, there will be complex residual stresses in the structure. The stress concentration in the process of welding joint force, the initial defects caused by welding joint welding process and the welding residual stress of the structure showing the tensile state of the welded joints lead to the fatigue performance of the welded joints. In order to accurately describe the actual stress field of welding joints under repeated loads, it is necessary to simulate the welding residual stress at first, and then superimpose the working stress amplitude of the structure caused by different load amplitude. The accurate simulation of welding residual stress is of great significance to the study of the fatigue performance of welding node.
In this paper, the ANSYS program is used to simulate the welding residual stresses of three typical welding details such as docking, T shape, U ribs and top plates, and the fatigue properties of the dangerous points of the welded joint are analyzed. The work of this paper has the following aspects:
1 according to the physical and mechanical parameters of Q345 under high temperature, the welding heat source model and the parameters of the welding process are determined. The moving load of the weld heat source is realized, and the accurate welding temperature field of three kinds of joints is obtained. The APDL command of the numerical simulation of the welding process of different welding joints is written.
2 the distribution of residual stress is calculated by calculating the temperature field of the temperature field and the indirect coupling of the stress field, and the distribution of residual stress is calculated. For the U ribs and the top plate joints, the equivalent residual stress increases with the increase of the thickness of the roof. The residual stress is slightly higher than the yield strength.
3 according to the nominal stress loading of three kinds of joint in the European standard, the actual stress of the three kinds of joint is calculated, and the more serious part of the stress concentration is selected as the danger point. The superposition of the residual stress and the actual stress obtained by this point is calculated. The new S-N curve of the dangerous point is drawn by the Goodman relation and the material S-N curve of the material. The calculation will be calculated. Results compared with the S-N curves of welded joints in European standard, the reasons for the difference of curves were analyzed, and two stress correction coefficients were proposed.
【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;U448.36
本文编号：2163837
[Abstract]:With the development of the bridge construction in China, the proportion of the steel structure and bridge is increasing, and a lot of welding details have appeared. The welding fatigue design in our country is relatively late, and there is no perfect standard of fatigue design for welding details. A heavy accident.
Welding is a complex process involving physics, chemistry and mechanics. After the welding is heated and cooled, there will be complex residual stresses in the structure. The stress concentration in the process of welding joint force, the initial defects caused by welding joint welding process and the welding residual stress of the structure showing the tensile state of the welded joints lead to the fatigue performance of the welded joints. In order to accurately describe the actual stress field of welding joints under repeated loads, it is necessary to simulate the welding residual stress at first, and then superimpose the working stress amplitude of the structure caused by different load amplitude. The accurate simulation of welding residual stress is of great significance to the study of the fatigue performance of welding node.
In this paper, the ANSYS program is used to simulate the welding residual stresses of three typical welding details such as docking, T shape, U ribs and top plates, and the fatigue properties of the dangerous points of the welded joint are analyzed. The work of this paper has the following aspects:
1 according to the physical and mechanical parameters of Q345 under high temperature, the welding heat source model and the parameters of the welding process are determined. The moving load of the weld heat source is realized, and the accurate welding temperature field of three kinds of joints is obtained. The APDL command of the numerical simulation of the welding process of different welding joints is written.
2 the distribution of residual stress is calculated by calculating the temperature field of the temperature field and the indirect coupling of the stress field, and the distribution of residual stress is calculated. For the U ribs and the top plate joints, the equivalent residual stress increases with the increase of the thickness of the roof. The residual stress is slightly higher than the yield strength.
3 according to the nominal stress loading of three kinds of joint in the European standard, the actual stress of the three kinds of joint is calculated, and the more serious part of the stress concentration is selected as the danger point. The superposition of the residual stress and the actual stress obtained by this point is calculated. The new S-N curve of the dangerous point is drawn by the Goodman relation and the material S-N curve of the material. The calculation will be calculated. Results compared with the S-N curves of welded joints in European standard, the reasons for the difference of curves were analyzed, and two stress correction coefficients were proposed.
【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;U448.36
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