基于固有应变法的环肋圆柱壳焊接残余应力数值分析

环肋圆柱壳是水下装备的主要承压部件,通常采用高强钢进行建造,对焊接残余应力等缺陷较敏感.为了得到不同肋骨布置方式下的焊接残余应力分布情况,首先采用试验和数值模拟的方法研究了高强钢焊接试板残余应力分布情况,验证了固有应变近似公式的适用性;然后,基于固有应变法针对内置、外置T型肋骨的圆柱壳的焊接残余应力进行数值分析,结果表明:两者壳板径向变形与实测资料较为一致,内置肋骨时,跨中壳板内凹,反之外凸;残余应力主要分布于焊缝部位,跨中壳板呈现压应力,内置肋骨的压应力要略大一些.     

Predicting the collapse of externally pressurised ring-stiffened cylinders using finite element analysis

This paper describes the application of finite element (FE) analysis to the prediction of the non-linear elasto-plastic collapse of ring-stiffened cylinders under hydrostatic loading. A range of legacy experimental test models have been analysed using FE idealisations generated using measured as-built shape data including out-of-circularity (OOC), frame alignment and tilt and other scantlings. The FE models also explicitly included the residual stresses caused by cold bending. Short and long ring-stiffened cylinders, which were designed to isolate interframe and overall collapse modes, respectively, were considered as were some intermediate length cylinders where the possibility of interactive collapse was also present. In general, the collapse pressures were predicted to within 6%. However, for some of the interframe collapse models, it was necessary to use the minimum measured plate thickness to achieve this. This was largely attributable to the limited measured plate thickness data.     

焊接残余应力对深潜器耐压球壳承载能力的影响

耐压球壳通常采用焊接方式将两个半球壳连接成整球,在焊缝处产生的接近材料屈服强度的焊接残余应力对球壳的承载能力有多大的影响,是否需要做焊后消除残余应力处理,将直接影响球壳的安全性和生产成本。而现有对球壳极限强度计算,无论是理论计算还是数值计算,均只考虑了球壳初始缺陷中的几何缺陷对球壳极限强度的影响。该文将在现有的耐压壳极限强度设计公式基础上,采用数值计算的方法对耐压球壳的焊接过程进行数值模拟,得到焊后球壳的焊接残余应力分布,并在此基础上考虑残余应力对球壳极限强度的影响,结果表明,对于大潜深厚球壳,焊接残余应力对耐压球壳承载能力影响不显著,为大深度潜器耐压球罐是否需做焊后消除残余应力处理提供了一定的参考依据。     

自升式平台桩腿焊接变形和应力控制技术研究

自升式平台的桩腿由多段大厚度高强钢圆筒拼接而成,需要大量的多层多道焊工艺,导致复杂的焊接变形与残余应力,是桩腿加工精度和安全性检验中需要格外关注的问题。焊接变形、应力与焊接工艺参数和工艺措施有关,因此本文选取了四项对焊接变形、应力有重要影响的工艺参数：预热温度,保温缓冷措施,焊接速度和约束条件,通过热弹塑性有限元计算,分析这四项工艺参数对圆筒圆度、应力极值的影响,并基于对焊接变形与应力的综合控制,提出了工艺优化建议。     

焊接诱导的残余应力对加劲板轴向极限强度影响的简化模型研究（英文）

The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies(IACS) Common Structural Rules(CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.     

A Simplified Model for the Effect of Weld-Induced Residual Stresses on the Axial Ultimate Strength of Stiffened Plates

The present work investigates the compressive axial ultimate strength of fillet-welded steel-plated ship structures subjected to uniaxial compression, in which the residual stresses in the welded plates are calculated by a thermo-elasto-plastic finite element analysis that is used to fit an idealized model of residual stress distribution. The numerical results of ultimate strength based on the simplified model of residual stress show good agreement with those of various methods including the International Association of Classification Societies (IACS) Common Structural Rules (CSR), leading to the conclusion that the simplified model can be effectively used to represent the distribution of residual stresses in steel-plated structures in a wide range of engineering applications. It is concluded that the widths of the tension zones in the welded plates have a quasi-linear behavior with respect to the plate slenderness. The effect of residual stress on the axial strength of the stiffened plate is analyzed and discussed.     

焊接初始缺陷对船体梁极限弯矩的影响

对焊接初始缺陷于船体梁极限弯矩的影响进行了研究.采用热传递分析得到焊接结构的温度场,进而采用热弹塑性分析得到结构的焊接残余应力和焊接变形.将得到的焊接变形及残余应力作为结构的初始缺陷,对船体梁的极限弯矩进行了比较计算.结果表明,焊接初始缺陷对船体梁极限弯矩的影响不宜忽略,热传递及热弹塑性分析的方法可较好地模拟船体梁极限弯矩分析中的焊接初始缺陷.     

低周疲劳载荷下考虑累积塑性的船舶裂纹板剩余极限强度研究

研究表明在恶劣海洋环境中船体结构整体断裂破坏往往是低周疲劳破坏和累积塑性破坏的耦合结果。考虑这两者耦合作用的影响,评估船体结构的极限承载力更为实际。基于累积塑性和低周疲劳裂纹扩展,从理论上分析了平面内低周疲劳载荷下裂纹板的残余极限强度。经过一系列数值模拟,首先讨论低周疲劳裂纹扩展行为的影响,然后随着疲劳裂纹扩展的发展,主要讨论了初始变形,焊接残余应力,裂纹扩展长度,裂纹分布和裂纹板厚度对低周疲劳载荷下船体裂纹板极限强度的影响。     

基于强化散热的焊后冷源宽度对焊接残余应力的影响

鉴于冷源长度方向尺寸对焊趾位置残余应力峰值的影响不大，本文着重分析冷源宽度方向尺寸对焊后残余应力的影响。本文利用干冰作为焊后冷源介质跟随焊枪同步运动，基于热弹塑性有限元方法，对AH36高强钢薄板随焊激冷的焊接方法进行了模拟。分析了冷源相对于焊缝的宽窄关系对随焊激冷控制残余应力的影响，从而可以对干冰的喷嘴形状设计进行指导，以优化焊后冷源控制应力应变的效果，推进“低应力无变形”焊接技术在船舶领域的发展与应用。结果表明，在焊后施加冷源可以达到降低低应力无变形的效果。其中，在所施加焊后冷源宽度较焊缝宽的情况下，较其他两种宽度冷源控制应力与变形的效果更佳，板中心纵向残余应力可由常规焊的484Mpa减少到375Mpa，减少了109Mpa。     

凹型加肋锥-环-柱结合壳强度的模型试验研究

为考察凹型加肋锥-环-柱结合壳的力学行为,设计制作了3个凹型加肋锥-柱/锥-环-柱结合壳系列精车模型,采用分区样条等参元方法对它们进行了应力计算.分别对3个模型进行了静水外压试验,测量其应力,计算应力与实测应力吻合较好.模型试验和计算结果表明,凹型加肋锥-环-柱结合壳能有效降低锥、柱壳结合部的应力峰值.通过对模型试验结果的分析,得出了一些对指导凹型加肋锥-环-柱结合壳结构设计有实用价值的结论.     

船体梁极限强度的近似计算

船体梁的总纵强度是反映船舶结构安全可靠的最基本的强度指标。船体结构极限强度评估对于船舶结构初步设计、使用、维护和维修都非常重要，因此船体梁极限强度研究成为近几十年来船舶工程界的热点研究课题之一。到目前为止有两种典型的加筋板和船体梁的极限强度分析方法，它们是直接计算法和逐步破坏分析法。本文基于加筋板单元的平均应力应变曲线和逐步破坏分拆方法，提出了加筋板和船体梁极限强度的简化分析方法，考虑了初始挠度和残余应力对加筋板单元极限强度的影响。数值结果表明，采用本文简化方法得到的结果与有限元计算结果或其它逐步破坏分析结果比较符合。     

加肋锥—环—柱组合壳强度及稳定性模型实验研究

本文进行了加肋锥－环－柱组合壳应力、稳定性模型实验，并运用分区样条等参元法进行了数值计算，计算结果与实验结果吻合良好。还将加肋锥－环－柱组合壳与相应加肋锥－柱组合壳应力、稳定性特性进行比较。研究结果表明，加肋锥－环－柱组合壳是锥壳与柱壳间一种优越的连接形式。     

基于完整船体极限强度和搁浅剩余强度的协调共同结构规范对比分析

文章基于Smith法,根据国际船级社协会发布的2013版协调共同结构规范(HCSR)中破损模型、失效模式和载荷模型,考虑材料屈服、结构单元屈曲及后屈曲的特性,应用FORTRAN程序设计语言编写船体极限强度计算程序,以某76000吨散货船为算例,对完整船体的极限强度进行计算,对搁浅状态下破损船体的剩余强度进行计算并校核承载能力。通过在中拱和中垂工况下与其他规范的对比验证,2013版HCSR指定的剩余强度校核公式及船体梁载荷计算公式中选取的安全系数要求更高,校核更严格。     

联合弯矩作用下含裂纹船体结构剩余极限强度评估方法研究

裂纹损伤对于船体结构来说难以避免,将削弱结构的极限强度,所以研究含裂纹损伤船体结构的剩余极限强度意义重大.对于含裂纹舱段结构,现有的研究主要针对垂向弯矩作用下的剩余极限强度,对于联合弯矩作用下的研究还很欠缺.本文采用非线性有限元分析方法,研究了垂向弯矩和水平弯矩联合作用下含裂纹舱段的剩余极限强度.提出了计算含裂纹船舯舱段在联合弯矩作用下剩余极限强度的计算公式,通过对含裂纹箱型梁的有限元计算结果进行拟合,得到公式中待定系数的表达式.研究结果表明,本文提出的方法可以快速预测船体结构在联合弯矩作用下的剩余极限强度.     

T形焊接接头残余应力与变形的三维数值模拟

焊接残余应力和变形是个长期困扰船舶行业的难题。本文介绍了预测焊接残余应力和变形的基本数值理论,用MSC.Marc有限元分析软件对T形接头的焊接过程进行了实时三维数值模拟,并对焊接温度场、残余应力分布以及角变形计算结果进行了分析说明。     

超大型集装箱船用超高强度钢EH47焊接残余应力模拟与实验研究

超高强度钢EH47广泛应用于超大型集装箱船舱口围板等区域结构中,建造过程中常常伴随着较大的焊接残余应力,直接影响到船体结构的安全及使用寿命。论文基于有限元分析软件ANSYS,对平板对接焊进行模拟,得到焊接残余应力的大小和分布,并采用盲孔法对焊缝区域进行残余应力测量。结果表明:残余应力在靠近焊缝中心及区域附近处表现为拉应力,随着逐渐往焊缝中心靠拢,拉应力迅速增大,当达到焊缝中心附近时拉应力达到最大值。随着逐渐远离焊缝中心,拉应力迅速减小,达到一定距离时转变为压应力,并在距离焊趾2.5 cm处达到压应力最大值,数值模拟结果与试验测量值基本吻合,同时焊后热处理能有效降低有损结构强度的焊接残余应力。     

考虑筋/板相互作用的环肋圆柱壳屈曲强度分析

环肋圆柱壳是潜艇耐压壳体的一种主要结构形式.环肋圆柱壳的失稳破坏主要表现在肋骨间的壳板失稳和总体失稳.在计算肋骨间的壳板失稳时,传统方法认为肋骨为壳板提供简支边界,忽略了在边界上肋骨和壳板的相互影响.在实际结构中,由于肋骨提供扭转刚度,壳板在与肋骨相交的边界上将存在弯矩,并非自由支持边界.因而,壳板失稳时,筋/板产生相互影响,提高了壳板的屈曲强度.本文的主要目的是,推导考虑筋/板相互影响的环肋圆柱壳壳板屈曲强度的理论计算方法,分析筋/板的相互关系.通过本文的算例表明,本文推导的计算方法以及所编制的计算程序是可靠的,可以用于工程设计.     

Prediction of residual stresses induced by low transformation temperature weld wires and its validation using the contour method

Welding residual stresses are one of the main factors influencing the engineering properties of welded structures, and should be taken into account during designing and manufacturing products such as ships, bridges, etc. Recently, both computational and experimental methods play a significant role for providing residual stresses. The contour method (CM) became one of the most powerful techniques that can provide measurement of residual stresses normal to a plane of interest. In this method a component is cut at any plane of interest. Displacements normal to the cut surface are measured and then processed. Using the Thermal–Elastic–Plastic Finite Element Method (TEP-FEM), residual stresses after welding can be predicted. As well as, the elastic FEM can be used to reproduce residual stresses from measured longitudinal displacements in the CM.The main objective of this paper is to evaluate the effectiveness of different low transformation temperature (LTT) weld wires using TEP-FEM and the CM. In the simulation part, a computational approach is developed to numerically simulate both of welding and the CM. In the TEP-FEM, phase transformation is considered for LTT welds, additionally volume change and variation of mechanical properties with temperature are considered. In the simulated CM, welded specimens to be measured are replaced by TEP-FE models. Then the procedure of the CM is examined before applying it to real measurements. The simulated CM successfully predicted how the CM would reconstruct the residual stresses if applied experimentally. In the experimental part, welding is conducted using conventional and various LTT weld wires. Longitudinal residual stresses produced due to welding are measured using the CM. The results of TEP-FE simulation and the CM show the effectiveness of the different LTT weld wires in introducing compressive stresses in the weld. It is also observed that the applied LTT weld wires, which have almost the same martensitic transformation start temperatures, do not show big difference in the induced compressive residual stresses in the weld metal.     

焊接残余应力对疲劳寿命影响的定量研究

在以往的研究中,残余应力对疲劳寿命的影响基本上均局限于定性分析,很少给出定量的研究结果。文章基于双参数统一方法,开展了锥柱结合壳处的残余应力对疲劳寿命的定量计算分析,给出了残余应力对疲劳寿命影响范围,并通过试样疲劳试验进行了验证。通过研究,可以看出残余应力没有改变裂纹的扩展趋势,但明显加快了裂纹扩展的过程,明显降低了耐压结构的疲劳寿命。     

散货船碰撞损伤后的剪切极限强度

船体梁受到碰撞损伤后,必须有足够的剩余强度用以抵抗最大外弯矩,同时还需能够承受最大剪力.在众多类型的船舶中,散货船是一种抗剪能力较差的船型.对于其碰撞损伤后纵向剩余极限弯矩的研究已有较多的文献[2-7],而对于碰撞损伤后的剪切极限强度的研究目前还比较少.针对这一现状,本文的主要目的在于分析讨论散货船受到碰撞损伤后的极限承剪能力;分析结构几何尺寸,碰撞损伤形状以及边界条件等各种因素对碰撞破损船体抗剪能力的影响.为了方便起见,文中也给出了相应的回归经验公式.本文同时还推导了一个船体梁碰撞损伤后的初始屈服剪力计算公式.最后,本文以一艘散货船为例,计算分析其碰撞损伤后的抗剪能力,从中得出一些有益的结论.