铸钢节点环形对接焊缝残余应力分析

发布时间：2019-03-23 16:22

【摘要】：铸钢节点与普通钢管的连接方式主要是焊接,焊接产生的残余应力通常可达到屈服强度,会严重影响结构的疲劳强度。近些年来,国内外学者对环形对接焊缝的焊接残余应力已做出了一些研究,但研究对象主要针对的是薄壁、等厚的管线钢管或不锈钢管道的环焊缝,研究结果集中在残余应力分布方面,缺少参数化分析,而铸钢圆管与普通圆管焊接时两者壁厚一般不等,这种情况研究较少。本文在热-弹塑性理论的基础上,以环形对接焊缝连接的G20Mn5铸钢圆管和Q345普通圆管为分析对象。选择内生热率热源模型模拟焊接热输入,利用生死单元技术模拟焊接填充过程。选取Q345普通圆管的径厚比d/t、G20Mn5铸钢圆管与Q345圆管的壁厚比T/t以及Q345圆管的壁厚t为分析参数,分析得出了构件内、外表面沿其长度、圆周方向的焊接残余应力分布。同时,指出了不同分析参数对残余应力的影响,并提出了可供工程参考的残余应力的范围。通过以上分析,得出下列结论:(1)对于铸钢节点环形对接焊缝多层焊接的有限元模拟,内生热率热源模型比双椭球热源模型更为适合。(2)在焊缝金属区,随d/t的增加,构件内、外表面沿其长度方向的残余压应力增大,内表面沿其圆周方向的残余拉应力增大而外表面沿该方向的残余拉应力无明显变化;随T/t的增加,构件内表面沿其长度方向的残余压应力增大而外表面沿该方向的残余压应力减小,内、外表面沿其圆周方向的残余拉应力无明显变化;随t的增加,构件内表面沿其长度方向的残余压应力增大且外表面沿该方向的残余拉应力也增大,构件内表面沿其圆周方向的残余拉应力减小而外表面沿该方向的残余拉应力增大。(3)当d/t、T/t及t的取值均在常用范围之内时,构件内表面沿其长度方向的残余应力最大值为压应力,最大值范围:87.5~150N/mm2;构件外表面沿其长度方向的残余应力最大值为拉应力,最大值范围:115~155N/mm2;构件外表面沿其圆周方向的残余应力最大值为拉应力,最大值范围:205~245N/mm2;构件内表面沿其圆周方向的残余压应力最大值范围:70~135N/mm2;构件内表面沿其圆周方向的残余拉应力最大值范围:60~160N/mm2。
[Abstract]:The joint of cast steel joint and ordinary steel pipe is mainly welded, and the residual stress produced by welding usually reaches yield strength, which will seriously affect the fatigue strength of the structure. In recent years, scholars at home and abroad have made some research on the welding residual stress of circular butt weld, but the research object is mainly aimed at the ring welding seam of thin-walled and equal thickness pipeline pipe or stainless steel pipe. The results are concentrated on the distribution of residual stress and lack of parametric analysis. However, the wall thickness of the cast steel pipe is generally different from that of the ordinary pipe, which is less studied. On the basis of thermal-elasto-plastic theory, G20Mn5 cast steel pipe and Q345 ordinary pipe connected by ring butt weld are analyzed in this paper. The internal heat rate heat source model is selected to simulate the welding heat input, and the birth and death element technology is used to simulate the welding filling process. The diameter-thickness ratio of Q345 ordinary tube, the ratio of wall thickness of G20Mn5 cast steel pipe to Q345 pipe and the thickness t of Q345 circular tube are selected as the analytical parameters. The distribution of welding residual stress along the length and circumference of the inner and outer surfaces of the component is obtained. At the same time, the influence of different analytical parameters on residual stress is pointed out, and the range of residual stress for engineering reference is put forward. Based on the above analysis, the following conclusions are drawn: (1) for the finite element simulation of multi-layer welding of ring butt welds of cast steel joints, the endogenous heat rate heat source model is more suitable than the double ellipsoidal heat source model. (2) in the weld metal region, the heat source model is more suitable than the double ellipsoid model. With the increase of d, the residual compressive stress on the outer surface of the component increases along its length direction, while the residual tensile stress on the inner surface increases along its circumferential direction, while the residual tensile stress on the outer surface does not change significantly in this direction. With the increase of T _ (t), the residual compressive stress on the inner surface of the component increases while the residual compressive stress on the exterior surface decreases in this direction, while the residual tensile stress on the outer surface along its circumferential direction has no obvious change. With the increase of t, the residual compressive stress on the inner surface of the component increases in the direction of its length, and the residual tensile stress on the outer surface increases in that direction. The residual tensile stress on the inner surface of the component decreases in the circumferential direction, while the residual tensile stress on the outer surface increases in that direction. (3) when the values of d, T and t are within the common range, The maximum residual stress on the inner surface of the component is compressive stress, and the maximum value is 87.5 ~ 150N / mm ~ (2), the maximum value is 87.5 ~ 150N ~ (2) mm ~ (2); The maximum residual stress on the outer surface of the component is tensile stress, and the maximum residual stress along its circumferential direction is the tensile stress, and the maximum value is 205 ~ 245 N ~ (?) mm ~ (2), and the maximum value is 115 ~ 155 N / mm ~ (2) in the outer surface of the component, and the maximum residual stress in the outer surface of the member is the tensile stress in the circumferential direction of the member. The maximum residual compressive stress of the inner surface of the component along its circumferential direction: 70? 135N? Mm2?; the maximum residual tensile stress of the inner surface of the component along its circumferential direction: 60? 160N? Mm2.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU758.11;TG457.11

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