铸钢节点的抗疲劳优化设计

发布时间：2018-04-03 05:11

本文选题：铸钢节点　切入点：环形对接焊缝　出处：《东南大学》2015年硕士论文

【摘要】：现代工程结构跨度大、造型复杂、形式多样,对连接节点要求更加严格。相比于传统的节点连接方式,铸钢节点凭借着良好的力学性能、造型灵活、施工方便等优点,逐渐广泛的应用于国内外的建筑工程中。近年来,工程设计人员以及相关学者认识到铸钢节点的最大优点在于对结构抗疲劳性能的改善,并越来越多的应用于疲劳问题突出的结构。已有研究表明：铸钢节点的疲劳性能分为铸钢材料的疲劳性能和环形对接焊缝的疲劳性能两部分,铸钢材料的疲劳性能优于焊缝的疲劳性能,环形对接焊缝的疲劳性能在节点整体疲劳性能中起控制作用。相比于传统的节点连接方式,铸钢节点虽有众多优点,但铸钢材料不可避免的会产生缺陷,由于对其带缺陷疲劳性能研究不足,和相关环形对接焊缝的疲劳性能数据缺乏,工程设计中多采用放大安全系数的设计方法。因而,现有铸钢节点的设计方法比较保守,其疲劳性能,尤其是铸钢材料部分的疲劳性能存在着较大的冗余,造成节点自重大,浪费材料,增加建造成本。针对以上问题,本文对铸钢节点环形对接焊缝的疲劳性能进行试验研究；通过有限元方法对带缺陷铸钢材料的疲劳性能进行分析；依据铸钢节点疲劳性能研究成果,结合工程优化技术,对铸钢节点进行抗疲劳优化设计,首先对节点铸钢部分几何尺寸进行优化,得到节点轻量化最优尺寸,而后验算焊缝强度,修正局部尺寸,完成优化目标。本文主要研究内容如下：1.调研了国内铸钢节点环形对接焊缝使用现状,本文设计了两种常用焊接细节的铸钢节点弧形板小试件,进行了疲劳试验,对试验试件进行断面分析,对实验数据进行处理,采用数理统计方法,拟合了两种焊缝细节的均值S-N曲线与p-S-N曲线,并与相似的焊接细节疲劳数据进行了对比分析。将本项目四种焊缝细节视为一类焊缝的大样本,并采用数理统计方法拟合其p-S-N曲线,选取拟合下限S-N曲线作为铸钢节点环形对接焊缝统一S-N曲线,并推荐工程设计参考。2.建立了铸造初始缺陷的疲劳损伤累积计算方法。介绍了参数化设计方法,详述了铸钢节点参数化模型的建立过程,本文使用三维建模软件Pro/Engineering对杭州湾跨海大桥海中平台观光塔下节点建立了参数化模型；然后,依据疲劳损伤理论,使用ANSYS软件,详述了带缺陷的铸钢节点疲劳损伤累积计算方法。3.依据本文环形对接焊缝的疲劳试验研究成果,并结合东南大学陈达对铸钢节点环形对接焊缝的热点应力数值研究成果,给出了国内常用焊缝细节的热点应力寿命曲线(Shs-N曲线),为铸钢节点抗疲劳优化设计中焊缝寿命计算提供依据。4.针对铸钢节点的疲劳性能特点,基于已有的关于铸钢节点疲劳性能研究成果,本文提出基于疲劳性能的铸钢节点优化设计方法：1)建立节点参数化模型；2)通过灵敏度分析优化筛选设计变量；3)以节点质量最小为优化目标,以节点铸钢材料缺陷位置处疲劳损伤限值为约束条件,采用最优拉丁超立方全局抽样与梯度算法局部寻优的组合优化策略,对节点铸钢部分几何尺寸进行优化；4)采用热点应力法验算节点环形对接焊缝的疲劳寿命,对不满足疲劳寿命要求的焊缝局部参数进行修正,最终完成优化目标。本文以杭州湾跨海大桥海洋平台观光塔下节点为算例,采用铸钢节点抗疲劳优化设计方法进行优化,在满足节点整体疲劳性能的要求下,节点质量相比原设计方案降低了23.3%。
[Abstract]:Modern engineering structure of large span, complex shape, a variety of forms, more strictly to the connection requirements. Compared with the traditional connection mode, with the mechanical properties of cast steel joints, good design flexibility, the advantages of convenience, is widely used in domestic and foreign construction engineering. In recent years, engineering design and related personnel scholars recognize that the biggest advantage of cast steel joints on the anti fatigue performance of structure is improved, and more and more applied to the fatigue problems of structure. It has been shown that the fatigue properties of cast steel joints for fatigue properties of cast steel material and ring butt weld fatigue performance of the two part, fatigue performance is better than that of the weld steel material the fatigue performance of annular butt weld control node in the whole fatigue performance. Compared with the traditional connection mode, although the cast steel joints Many advantages, but the steel material will inevitably have defects due to the fatigue performance of belt defects, fatigue performance data and girth butt weld lack of amplification factor of safety design method used in engineering design. Therefore, the existing design method of cast steel joints is more conservative, especially the fatigue performance, fatigue performance there is a large part of the cast steel nodes caused by redundancy, since the great waste of material, increase the cost of construction. To solve the above problems, the fatigue performance of weld in experimental research; through the finite element method to analyze the fatigue properties of cast steel with defects on fatigue properties of cast steel joints; research combined with the engineering optimization technology to optimize the design of anti fatigue of cast steel joints, the cast steel joints geometry dimension optimization, get the day Some lightweight optimal size, and then check the weld strength of the modified local size, complete the optimization objectives. The main research contents of this paper are as follows: 1. the research of the domestic girth butt weld using situation, this paper designed two kinds of cast steel joints arc plate small specimen common welding details, fatigue tests were conducted for analysis of test section the specimen, the experimental data were processed by using the method of mathematical statistics, the mean fitting S-N curves and p-S-N curves of two kinds of weld details, and compared with similar welding. This project will detail fatigue data of four kinds of weld details as a kind of large sample weld, and fitted by the method of mathematical statistics the p-S-N curve, S-N curve fitting selection limit as the weld unified S-N curve, and the establishment of the fatigue damage of original casting defects was recommended reference in engineering design.2. Product calculation methods are introduced. The parametric design method, introduces in detail the construction process parameters of cast steel joint model, this paper uses 3D modeling software Pro/Engineering on the Hangzhou bay bridge tower under the platform node parametric model is established; then, based on the fatigue damage theory, the use of ANSYS software, describes the fatigue of cast steel joints the cumulative damage with defects based on the calculation method of.3. ring butt weld fatigue test results, combined with Southeast University Chen Da focuses on the weld should be given numerical research results, the details of the domestic hot common welding stress life curve (Shs-N curve), for cast steel joints fatigue life design and optimization of weld line in the calculation of.4. provide the basis for the fatigue properties of cast steel joints, based on the existing research results on fatigue properties of cast steel joints, is proposed in this paper. Optimization design method of cast steel joints based on Fatigue Performance: 1) the establishment of joint parameters model; 2) through the sensitivity analysis of optimization design variables; 3) to the node quality as the optimizing goal, to the position of defect of cast steel joints fatigue damage limit as constraint conditions, the optimal Latin hypercube sampling and global gradient algorithm combination optimization strategy of local optimization, the cast steel joints geometry dimension is optimized; 4) the focus should be on fatigue life force method for checking the bus ring butt weld, the weld parameters to meet the requirements of the Bureau of the Ministry of the fatigue life correction, finally completed the optimization objectives. In this paper, the Hangzhou Bay Bridge Tower of offshore platform under node for example, the cast steel joints fatigue optimal design method for optimization on fatigue properties of nodes meet the overall requirements, compared to the original design scheme of node quality drop Low 23.3%.

【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU511.3

【参考文献】