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Ju2000E自升式钻井平台的桩腿TKY节点由于焊接结构复杂,各构件采用高强度大厚板,焊缝多且不规则,焊接残余应力分布复杂,对其评估焊接残余应力非常困难。如今焊接残余应力表面测量配合应力计算是最有效的方法,本文采用一系列的高效计算方法实现了桩腿TKY节点焊接残余应力的高效计算,并通过X衍射法和小孔法验证了计算的可靠性,同时通过计算机模拟软件建立的三维实体模型分析了该结构的应力分布特征。计算结果表明,整个模拟件各方向的峰值拉应力出现在半圆板焊接区域表层,特别是焊趾位置呈现较大的应力集中,而焊缝材料的屈服强度相对半圆板材料屈服强度低,故焊缝区域的各方向拉应力幅值稍低于半圆板焊接区域;整个模拟件各焊缝区域从外到内部的等效应力呈现300-600MPa的较大应力,靠近半圆板的焊趾位置出现较大应力集中,等效应力达到600MPa以上。 相似文献
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在船体板架的焊接工序中,由于制造误差产生的纵骨错位问题对焊接过程及焊接质量产生不利影响。以典型船体板架为例,在纵骨强制对齐的基础上采用顺序耦合的热弹塑性有限元法对其焊接过程进行数值仿真分析,研究纵骨错位量对焊接变形和应力的影响规律。结果表明,随着错位量的增加,错位纵骨两侧板格焊接变形分布的不对称性逐渐增强,左右两侧板格变形差值最大可增加3.7倍,且当错位量一定时,外板厚度越小纵骨错位的影响越大。此外,纵骨强制装配产生的应力与板架焊后残余应力均随错位量的增大而增加,当错位量为10 mm时,残余拉应力与压应力分别是纵骨未错位情况下的4.4倍与4.9倍。 相似文献
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对海洋工程大厚度高强钢焊接结构焊后焊缝及母材进行局部超声冲击处理,采用X射线衍射法和小孔法测试冲击前后的残余应力,分析超声冲击工艺对焊接残余应力的影响.研究结果表明:大厚度高强钢焊接结构经覆盖焊缝及母材局部超声冲击处理后,焊接残余应力显著降低,冲击区域拉应力全部转化为压应力,压应力大小均匀,XRD测试压应力均值达到母材理论屈服强度的0.50~0.80倍,小孔法测试压应力均值达到母材理论屈服强度的1.10~1.30倍;EQ47拘束态高强钢焊接结构分别采用冲击强度10 s/cm2与20 s/cm2冲击后,冲击区域形成的压应力基本一致,纵向应力与横向应力大小接近,20 s/cm2冲击强度下纵向应力与横向应力接近水平优于10 s/cm2. 相似文献
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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。 相似文献
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Numerical simulation based on finite element modelling is used to study the influence of welding sequences on the distribution of residual stress and distortion generated when welding a flat-bar stiffener to a steel plate. The simulation consists of sequentially coupled thermal and structural analyses using an element birth and death technique to model the addition of weld metal to the workpiece. The temperature field during welding and the welding-induced residual stress and distortion fields are predicted and results are compared with experimental measurements and analytical predictions. The effect of four welding sequences on the magnitude of residual stress and distortion in both the plate and the stiffener is investigated and their effects on the ultimate strength of the stiffened plate under uniaxial compression are discussed. Appropriate conclusions and recommendations regarding the welding sequence are presented. 相似文献
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《船舶与海洋工程学报》2015,(3)
Submerged arc welding(SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress. 相似文献
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Submerged arc welding (SAW) is advantageous for joining high thickness materials in large structure due to high material deposition rate. The non-uniform heating and cooling generates the thermal stresses and subsequently the residual stresses and distortion. The longitudinal and transverse residual stresses and angular distortion are generally measured in large panel structure of submerged arc welded fillet joints. Hence, the objective of this present work is to quantify the amount of residual stress and distortion in and around the weld joint due to positioning of stiffeners tack. The tacking sequence influences the level of residual stress and proper controlling of tacking sequences is required to minimize the stress. In present study, an elasto-plastic material behavior is considered to develop the thermo mechanical model which predicts the residual stress and angular distortion with varying tacking sequences. The simulated result reveals that the tacking sequence heavily influences the residual stress and deformation pattern of the single sided fillet joint. The finite element based numerical model is calibrated by comparing the experimental data from published literature. Henceforth, the angular distortions are measured from an in-house developed experimental set-up. A fair agreement between the predicted and experimental results indicates the robustness of the developed numerical model. However, the most significant conclusion from present study states that tack weld position should be placed opposite to the fillet weld side to minimize the residual stress. 相似文献
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大型核电厚壁结构X射线衍射法残余应力测试 总被引:1,自引:0,他引:1
采用X射线衍射法( XRD)对大型核电厚壁结构堆芯板端面、堆芯板与吊篮筒体环焊缝焊前焊后残余应力进行无损测量。研究堆芯板端面、环焊缝焊前焊后残余应力的分布情况及变化规律。结果表明:堆芯板焊前残余应力主要是机加工应力,且焊接过程对其残余应力影响不大;1#和2#堆芯板环焊缝轴向残余应力分布趋势明显,呈现焊缝为压应力,母材为拉应力;测试的环向应力在各区域分布不一致;焊接对远离焊缝区域的应力没有影响,远离焊缝区域呈现较大的加工应力。 相似文献
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船体结构总纵极限强度的简化逐步破坏分析方法 总被引:2,自引:0,他引:2
本文基于Smith方法,应用梁-柱理论、理想弹塑性假设、平截面假设和塑性铰理论建立了加筋板单元的应力-应变关系曲线,导出了船体结构总纵极限强度的简化逐步破坏分析方法并编制成FORTRAN计算程序.应用作者导出的简化逐步破坏分析方法分析计算了Reckling 23号模型总纵极限强度.计算结果表明,本文导出的简化逐步破坏分析方法和计算程序正确可靠,可供船体结构设计和使用.本文还对船体结构总纵极限强度的影响因素进行了分析,其中包括加筋板单元的载荷-缩短行为、横向压力、材料屈服强度和腐蚀等. 相似文献
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对2块厚度为24mm的Ti-6Al-4VELI厚板进行夹角为171.98°的多层TIG焊接试验,基于SYSWELD软件平台,在焊板两端完全刚性固定的装夹条件下数值模拟计算焊接温度场、应力场和焊接引起的变形.计算结果表明,焊接温度场的变化规律符合实际,焊缝区的拉伸残余应力最大,热影响区的压缩残余应力较大.焊接数值模拟得到的残余应力场与试验测量值能较好地吻合,验证了数值模拟模型的准确性.该数值模拟方法可应用到大深度Ti-6Al-4VELI载人舱强度计算中的焊缝残余应力模拟中. 相似文献
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It has been reported that low transformation temperature (LTT) weld metals are beneficial to generation of compressive residual stress around weld zone. In this study, the relationship among residual stress, size effect of LTT welded joints with different plate width and thickness as well as martensite start (Ms) temperatures was investigated by experimental and finite-element analysis. It was found that heat dissipation and thermal expansion coefficient of LTT weld metal had a significant impact on residual stress. Welded joint with a small plate width led to greater compressive residual stresses in the LTT weld, which was due to the lower heat dissipation and smaller thermal expansion coefficient of the LTT weld metal in due course of cooling process. Additionally, the finite-element analysis revealed that increasing plate width mainly affected the longitudinal residual stress, while increasing the plate thickness influenced all the residual stress components in the LTT weld. Furthermore, the LTT weld with a lower Ms temperature of 191 °C resulted in greater compressive residual stresses, and was less sensitive to the LTT joint size, as against the Ms temperature of 398 °C. 相似文献
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The paper presents the results of metal inert gas T-joint fillet welding tests of small scale rectangular stiffened steel plates longer than the standard test specimen. In the literature the focus is typically on plates with a small aspect ratio and the present work deals with plates of higher aspect ratio, which are the typical ones in marine structures, aiming to determine if there is any significant effect of welding along the longitudinal direction. Nonlinear thermo-elasto-plastic finite element models are adopted to evaluate the temperature distribution, welding induced distortions and residual stress in the stiffened plates of shipbuilding steel. Given the difficulty in data acquisition of temperature-dependent properties of the material, a simplified model of the properties is proposed, based on the values at room temperature. Good agreement is observed between the measured and simulated temperatures, indicating that the current finite element approach is appropriate to simulate the welding process. The proposed simplified material model can be efficiently used in the finite element analysis of welded steel structures. It is concluded that the welding parameters have more significant influence on the structural responses than the dimension of the plate. 相似文献
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船舶焊接领域中,钢板等焊接不可避免的会产生焊接残余应力,针对这一问题,文章通过分析焊接机器人焊枪末端受电抖振及其扰动等影响来揭示其响应规律。首先通过搭建的焊接模型阐明焊接过程动力学特性,然后研究不同特性电弧力对焊枪运动稳定性的影响,探索末端焊枪作业稳定性与焊接区电弧力及电源频率等参量之间响应关系,并对多组不同驱动电频下的焊接运动进行动力学仿真,得到电频变化与电弧力的对应规律。研究表明,焊接电源频率的有效细化有利于末端焊枪焊接运动过程的平稳,且发现最优焊接电源频率在10HZ邻域时焊枪末端动态振动最小,通过控制电源频率大小能明显抑制焊枪振动,在一定程度上降低残余应力大小,有利于船舶焊接表面质量的提高。 相似文献