【作者】 袁志军；

【导师】 扶名福；

【作者基本信息】 南昌大学 ， 材料与加工工程， 2010， 博士

【摘要】 焊接球节点是大跨度钢结构中常用的节点形式,由于节点的成形特点节点焊缝中存在较高的残余应力。研究残余应力的大小与分布及其影响因素将有助于节点在工程中的应用。同时焊接数值模拟技术的发展也为焊接技术的发展创造了有力的条件,使得焊接技术正在发生着由经验到科学、由定性到定量的飞跃。综合利用数值模拟与实验方法可有效降低节点工程应用成本。本文利用现有通用有限元软件ANSYS,并结合其APDL二次开发功能,编制了单管与球焊接、双管与球焊接及四管与球焊接的几何与有限元建模程序；同时运用有限元提供的单元生死功能,编制了温度场与应力应变场分析计算控制程序。根据钢网架焊接球节点设计规程要求,系列化的分析了焊接参数中诸如钢球直径、壁厚、管径、焊接顺序及焊接速度对对温度场与应力场的影响,为工程实践提供参考与指导,在此基础上还对双管、四管在钢管焊接角度对其温度与应力场进行了分析研究,得到了各焊接节点处焊缝在不同路径上的应力分布情况。从损伤理论出发,结合初始应力问题基本理论,分析推导了在焊接损伤(初应力)下的解析过程；并利用ANSYS程序对比分析了无初始残余应力损伤及有初始焊接残余应力损伤下焊接球节点的静力力学性能,发现了焊接残余应力对焊接球节点静载荷承载力没有影响的规律,但对其节点刚度方面的削弱影响较为明显。为了解焊接模拟分析的可靠性,本文利用盲孔法对两对组球管焊接件的焊缝处残余应力进行了分析测试研究。实验分析表明,球管焊接节点焊缝应力测试时盲孔深度与钻孔钻头直径的关系,获得了部分控制点的焊接残余应力,结果表明实验应力与模拟应力较为吻合。本研究将有助于了解球管焊接节点的残余应力的分布情况及为控制残余应力大小的一些实用性方法,为该类节点工程应用提供基础。更多还原

【Abstract】 The welded hollow spherical joint is a common joint used in the long span steel structures, but there exists complicated residual stress in such joints for their weld forming way engendering residual stress easier. Researching on the residual stress distribution and magnitude can be helpful to the application of such joint in project. And the development of numerical simulation methods provides the vigorous condition for the progress of the welding technique, and conduces a leap from experience to science and from qualitative analysis to quantitative analysis in the welding technique development. It can be brought about a reduction in the practice cost in project when combining numerical simulation method with experiment method to solve welding residual stress problems.In this thesis the ANSYS software is applied to simulate the welding process. With its APDL language some programs are programmed to create the geometric model and FEM model in the case of single pipe, double pipes and four pipes with hollow sphere welding respectively, and to control the simulation of temperature, stress, and strain field with the birth and death function. As the design code of welded hollow spherical joint steel grid requested, some factors are considered about such as the diameter, thickness of hollow spheres and diameter of pipes and the welding speed and welding sequence to study its influence on the distribution and magnitude of temperature, stress, and strain field. The result can provide guidance and be consulted in projects. Based on the forenamed result, the influence on the distribution and magnitude of temperature and stress field in the case of double or four pipes welding with hollow sphere are studied about the degree between the tow pipes or four pipes, and the stress distribution in different path has obtained at the end.The resolving process on the welding damage problem is deduced in the thesis combining the damage theory and the basic theory of initial stress problems and the static mechanics performance of such joints are provided with comparative analysis between the one with initial stress damage and the one without by Ansys software. The conclusion can be draw that the initial stress is not influent to the static strength of the joint but to the stiffness reducing seriously.In order to check the reliability of the numerical simulation, two weld joints residual stress testing experiment are made with blindhole method in the weld. Through the experiment it can find the depth of the blindhole is related with diameter of drill and the simulation result is in keeping with the experiment result to a certain extent.All in all, the research will be helpful to know the residual stress distribution and the practical methods to reduce the residual stress in the joint and the result can be refered to in projects.更多还原