焊接热切高强H型钢的残余应力

构件中所存在的残余应力会大大影响钢结构组件的刚度和疲劳寿命。虽然对于低碳钢的结构部件有较多的研究,但由于在常温和高温下应力-应变关系和材料属性的不同,造成了残余应力分布在高强钢构件中与低碳钢焊接而成的构件中的差异。因此,有必要研究由高强钢焊接而成的结构部件中残余应力的分布。对3个屈服强度460MPa的焊接热切高强型钢柱的残余应力进行研究,对不同横截面大小也进行了分析。使用切片法和钻孔法测量,并对两种方法所获得的残余应力进行比较。所测量的残余应力的大小和分布与碳钢中的一致,然而却有相对更小的残余应力比。最后,根据所测量的值,提出一个简化的由热切H型钢焊接而成的460MPa高强钢构件的残余应力分布。     

激光焊接不锈钢工字形截面中长柱受力性能研究

为研究激光焊接奥氏体不锈钢工字形截面轴心受压中长柱的承载性能,对10根激光焊接不锈钢工字形薄柔截面中长柱进行轴心受压试验研究,结果表明,中长柱的破坏模式均为板件局部屈曲与构件整体弯曲屈曲的相关失稳。同时,基于残余应力试验,验证了已有激光焊接不锈钢工字形截面的残余应力分布模型。基于试验结果验证了有限元模型,对激光焊接不锈钢工字形截面轴心受压中长柱开展参数分析,研究了几何初始缺陷和残余应力对中长柱稳定承载力的影响,结果表明,残余应力是影响中长柱稳定承载力的主要因素。结合试验和有限元计算结果,对CECS 410:2015《不锈钢结构技术规程》中轴心受压构件稳定承载力设计公式的适用性进行评估,并考虑残余应力的影响修正了轴心受压构件整体稳定设计公式的计算系数。采用修正后计算系数的规范公式能准确计算激光焊接不锈钢工字形截面轴心受压构件的稳定承载力。     

不锈钢焊接工字形截面残余应力分布试验研究

通过焊接加工10个不锈钢工字形截面试件（选材包括奥氏体型S30408和双相型S22253两种），采用分割法将试件截面切分成条带，量测释放的残余应变，计算得出截面的残余应力大小与分布形态。结果表明：试件截面的残余拉应力峰值低于材料的名义屈服强度，对于奥氏体型S30408和双相型S22253两种不锈钢试件的截面残余拉应力峰值分别约为其名义屈服强度的80%和60%。基于试验结果对现有简化分布模型的评估表明其应用的局限性，提出可以较准确描述不锈钢焊接工字形截面残余应力分布的建议简化模型，结合现有的其他试验数据，对建议简化分布模型的适用范围进行了验证和推广，可以为不锈钢结构构件的稳定性研究和设计提供参考。     

焊接铝合金构件残余应力试验研究

迄今为止,我国有关焊接铝合金构件残余应力的研究还不多见.由于铝合金与钢型材的材性等方面有诸多不同,使得焊接对铝合金的影响变得更为复杂.作为焊接影响的一个重要方面,焊接残余应力的分布规律成为迫切需要研究的重要课题.为此,采用切片法对两种方式焊接的铝合金工字型截面构件的残余应力进行了测试.通过对测试数据的分析整理,得出纵向焊接工字型截面构件残余应力的分布情况.为进一步总结焊接铝合金构件残余应力的分布规律及研究残余应力对构件承载力的影响提供了基础.     

残余应力分布对焊接不锈钢工字形截面梁整体稳定性能的影响

焊接残余应力导致不锈钢梁截面纤维过早达到屈服,并严重降低不锈钢梁的抗弯刚度。为了研究残余应力对焊接工字形不锈钢梁侧扭屈曲的影响,根据目前被广泛采纳的不锈钢工字形截面残余应力分布模型,采用有限元方法,对残余应力分布模型的主要因素进行参数化分析,研究这些因素对不锈钢梁侧扭屈曲的影响,使对焊接工字形不锈钢梁的整体稳定性能的研究更加完善。结果表明:翼缘残余压应力峰值对不锈钢梁侧扭屈曲的影响最为显著。     

Q550GJ高强钢焊接箱形截面残余应力试验研究

为了研究国产Q550GJ高强钢焊接箱形截面构件的残余应力分布情况,根据其力学性能,设计和加工了6个Q550GJ高强结构钢焊接箱形截面构件,采用分割法对其进行残余应力试验。基于试验测量数据,得到不同试件的残余应力分布,研究板件宽厚比、板件厚度等几何尺寸对残余应力的影响。研究结果表明:高强钢Q550GJ焊接箱形截面构件的翼缘和腹板两端近焊缝区域出现较大的残余拉应力,翼缘和腹板中部呈现大小基本不变的残余压应力区,其余部位为由残余拉应力到残余压应力转变的过渡区域。随着宽厚比的提高,翼缘和腹板残余压应力值相应减小,残余拉应力值的变化规律不明显,有增大的趋势,且残余拉应力值均小于高强钢Q550GJ的屈服强度。在相同宽厚比情况下,焊接箱形截面构件厚度增加后,翼缘和腹板的残余压应力和残余拉应力相应减小。     

BS700对焊槽钢焊接残余应力分布及影响因素研究

以BS700对焊槽钢结构为研究对象,对其加工成型后的焊接残余应力分布规律及其影响因素进行研究。研究结果表明:对焊槽钢结构中的焊接残余应力分布以纵向残余拉应力为主,会严重影响对焊槽钢结构的稳定性和疲劳性能;两条焊缝的纵向残余应力分布虽然均处于拉应力区域,第2条焊缝焊趾处的纵向残余应力峰值更高;在等截面边长结构中的截面边长变化和非等截面边长结构中的长宽比变化主要对对焊槽钢结构中的横向残余应力分布产生影响,对结构中的纵向残余应力分布影响不大;槽钢壁厚的变化会显著影响结构中的横向、纵向焊接残余应力值,在槽钢尺寸设计过程中,应选取适当壁厚的槽钢,以减小焊接残余应力对对焊槽钢结构的影响。     

盾构隧道复合管片接头板焊接的数值模拟研究

焊接变形及残余应力的存在会对焊接构件的应用产生不利影响,进行结构构件焊接变形的高精度预测和残余应力的分布预测具有重要的工程意义。本文针对复合管片接头板构件,利用ABAQUS有限元软件建立复合管片面板及接头板的三维实体模型,同时考虑材料非线性、几何非线性和边界非线性,并基于热-弹-塑性有限元法对接头板四周的焊接进行了模拟,分析了不同焊接顺序、环境温度及拘束状态对接头板焊接变形和残余应力的影响。结果表明:焊接顺序对复合管片接头板的变形有明显影响,采用平行对称焊接,先焊接长焊缝,后焊接短焊缝的顺序可有效降低Z方向的变形量;环境温度会改变构件残余应力的分布,随着环境温度的升高,纵向残余拉应力逐渐较小,距接头板上边缘约140～280 mm范围内的压应力也减小,而其他范围内的压应力呈增大趋势;拘束状态对纵向残余拉应力的影响较小,对纵向残余压应力的分布影响较大,在相距600～840 mm范围内设置两个对称拘束可对焊接变形起到控制作用。     

不锈钢焊接箱形截面柱轴心受压相关稳定试验研究

不锈钢的非线性材料特性使其构件承载性能不同于普通钢结构构件,需要开展专门的研究。通过焊接加工8个不锈钢箱形截面柱,包括奥氏体型S30408和双相型S22253两种牌号,在试件两端铰接的约束条件下开展轴心承压加载试验。试验中对板材力学性能、试件的局部与整体几何初始缺陷、纵向焊接残余应力分布和加载初偏心进行了测量。加载试验得出了板件的局部屈曲承载力与构件的相关稳定承载力,展示了从组成板件局部屈曲到构件整体弯曲屈曲的渐变失效形态。将试验结果与欧洲不锈钢规范EN 1993-1-4、直接强度法和中国冷弯薄壁型钢结构技术规范GB 50018的计算公式进行比较表明,由于欧洲规范和直接强度法没有考虑不同牌号不锈钢材料力学性能的差异,对双相型S22253构件的承载力计算偏于保守,而奥氏体型S30408构件的计算承载力偏于不安全;而中国规范GB 50018没有考虑焊接残余应力、几何缺陷和材料非线性的不利影响,高估了构件的相关稳定承载力。所得到的试验结果将为后续的数值分析与理论研究提供数据支撑。     

用热浸锌部分消除焊接钢管结构残余应力试验研究

焊接钢结构中的残余应力对结构延性有害,一般采用多种附加措施来部分消除残余应力.为考察热浸锌对部分消除残余应力的作用,利用盲孔法,对比测量了焊接钢管结构中3种典型的焊接节点在热浸锌前后的残余应力,介绍了衡量残余应力消除效果的3个评价指标,分析了热浸锌前后残余应力的变化及其原因.研究表明,热浸锌对部分消除构件焊接残余应力具有积极作用,且不要附加投资.最后,给出了钢结构加工过程中的一些建议.     

Residual stresses in cold-rolled stainless steel hollow sections

Stainless steel exhibits a pronounced response to cold-work and heat input. As a result, the behaviour of structural stainless steel sections, as influenced by strength, ductility and residual stress presence, is sensitive to the precise means by which the sections are produced. This paper explores the presence and influence of residual stresses in cold-rolled stainless steel box sections using experimental and numerical techniques. In previous studies, residual stress magnitudes have been inferred from surface strain measurements and an assumed through-thickness stress distribution. In the present study, through-thickness residual stresses in cold-rolled stainless steel box sections have been measured directly by means of X-ray diffraction and their effect on structural behaviour has been carefully assessed through detailed non-linear numerical modelling. Geometric imperfections, flat and corner material properties and the average compressive response of stainless steel box sections were also examined experimentally and the results have been fully reported. From the X-ray diffraction measurements, it was concluded that the influence of through-thickness (bending) residual stresses in cold-rolled stainless steel box sections could be effectively represented by a rectangular stress block distribution. The developed ABAQUS numerical models included features such as non-linear material stress-strain characteristics, initial geometric imperfections, residual stresses (membrane and bending) and enhanced strength corner properties. The residual stresses, together with the corresponding plastic strains, were included in the FE models by means of the SIGINI and HARDINI Fortran subroutines. Of the two residual stress components, the bending residual stresses were found to be larger in magnitude and of greater (often positive) influence on the structural behaviour of thin-walled cold-formed stainless steel sections.     

Residual stress distributions in welded stainless steel sections

Residual stress magnitudes and distributions in structural stainless steel built-up sections have been comprehensively investigated in this study. A total of 18 test specimens were fabricated from hot-rolled stainless steel plates by means of shielded metal arc welding (SMAW). Two grades of stainless steel were considered, namely the austenitic grade EN 1.4301 and the duplex grade EN 1.4462. Using the sectioning method, the test specimens were divided into strips. The residual stresses were then computed by multiplying the strains relieved during sectioning by the measured Young׳s moduli determined from tensile and compressive coupon tests. Residual stress distributions were obtained for 10 I-sections, four square hollow sections (SHS) and four rectangular hollow sections (RHS). Peak tensile residual stresses reached around 80% and 60% of the material 0.2% proof stress for grades EN 1.4301 and EN 1.4462, respectively. Based upon the test data, simplified predictive models for residual stress distributions in stainless steel built-up I-sections and box sections were developed. Following comparisons with other available residual stress test data, the applicability of the proposed models was also extended to other stainless steel alloys. The proposed residual stress patterns are suitable for inclusion in future analytical models and numerical simulations of stainless steel built-up sections.     

Analysis of residual stress in stainless steel pipe weld subject to mechanical axial tension loading

This paper presents the characteristics of welding residual stresses in circumferentially butt-welded stainless steel pipe by utilizing three-dimensional (3-D) uncoupled thermo-mechanical finite element (FE) analysis method. Moreover, stress variations in welded joints of the pipe under superimposed mechanical axial tension loading are further investigated employing the welding residual stresses and plastic strains obtained from the thermo-mechanical FE analysis as an initial condition. Results show that spatial variations of the welding residual stresses are present along the circumference and a rapid change of the residual stresses exists at the welding start/stop position, hence 3-D FE analysis is essential to accurately simulate circumferential welding of a pipe component. When mechanical axial tension loading is applied to the circumferentially butt-welded stainless steel pipe, bending moment is generated at the welded joints caused by the circumferential shrinkage of the weld region during welding; thus affecting the axial and hoop stress evolutions in the course of the superimposed mechanical loading.     

热应力法在钢结构焊接疲劳模拟中的应用

基于ANSYS平台,给出了间接热应力法计算焊接残余应力的计算流程。以V型坡口钢板为例,利用APDL语言编程,获得了焊接温度场及残余应力场的分布规律,计算结果与实测结果比较吻合。对于进一步研究焊接疲劳具有指导意义。     

高强度钢焊接节点残余应力对应力集中系数的影响

对一系列由屈服应力为690MPa的高强度钢板焊接而成的T型和Y型节点试件进行研究。节点焊接方式为电弧焊(SMAW)。两组试件分别采用不同的焊接工艺:一组试件在常温状态进行焊接,另一组将试件预热至100℃再进行焊接。研究两组试件靠近焊趾处的残余应力。首先,采用钻孔法研究节点的残余应力分布及变化;然后,采用ABAQUS有限元软件进行热应力耦合分析以研究节点的残余应力分布;最后,评估节点处残余应力对应力集中系数的影响。结合残余应力影响给出评估应力集中系数的新参数。     

Experimental investigation and modeling on residual stress of welded steel circular tubes

To investigate the residual stress of welded steel circular tubes, an experimental program including 9 different sectional dimensions and different steel strength specimens were described in which sectioning method was employed. Based on large quantities of original test data, the residual stress distribution and the magnitudes of these different specimens were obtained, and the effects of the diameter to thickness ratio, the steel strength and hot galvanizing process as well as welding types were analysed. It was found that the residual stress distribution of high strength steel welded tubes was flatter than the ones of ordinary steel tubes, and galvanizing process decreased the maximum residual tensile stress. Finally, the residual stress distribution model for steel welded circular tube sections was proposed which showed good agreement with the test results. Meanwhile, the finite element verification was carried out which provided reference for the future FEA of column buckling of high strength steel circular tubes. The research results provide foundation for the future study on the column buckling of welded steel circular tubes.     

Influence of residual stress on stress concentration factor for high strength steel welded joints

In this study, a set of plate-to-plate T and Y joints specimens made from high strength steel plates with yield stress equal to 690 MPa is investigated. The joints are fabricated by SMAW welding procedure. Two groups of specimens with different welding procedures are included: one group is composed by the joints with welding completed at ambient temperature and the other group is composed by the joints with welding completed at a preheating temperature of 100 °C. The residual stress near the weld toe is investigated for both groups. Hole-drilling method is applied to investigate the residual stress distribution and variation in joints. Sequentially coupled thermal-stress analysis is then conducted with finite element package ABAQUS to investigate the residual stress distribution in the joints. Finally, the effects of residual stress on the stress concentration factor distributions of the joints are evaluated. A new parameter is put forward in stress concentration factor evaluation to combine the residual stress effect.