共查询到18条相似文献,搜索用时 126 毫秒
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为了解焊接残余应力及其释放规律,基于顺序耦合热力学有限元方法对ABAQUS软件进行二次开发,模拟平板对接焊的焊接过程,计算焊接残余应力分布及其在0.8σ_s循环拉伸载荷作用下的释放情况,同时开展相应的试验研究,验证有限元计算方法的有效性。讨论循环载荷大小对残余应力释放的影响,计算3种不同水平载荷下焊接残余应力释放情况,得出AH36钢对接焊平板残余应力释放计算公式,通过对比有限元计算结果与试验结果,表明残余应力释放公式具有较好的计算精度,可以用于估算不同载荷作用后焊接残余应力的释放。 相似文献
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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。 相似文献
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高强度钢材料对焊接残余应力非常敏感,严重影响FPSO的安全可靠性,因此有必要对FPSO典型焊接节点的残余应力进行分析研究.文中选取能代表FPSO典型焊接结构形式的一种焊接节点进行试验研究,采用X射线无损检测法,对典型焊接节点的残余应力进行试验测量.根据试验测量结果,分析了FPSO典型焊接节点的残余应力分布规律. 相似文献
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由于浮式生产储油卸油船(FPSO)等船舶结构在服役前常常经历过较大的静载荷,这个预载荷常常会使焊接接头处较高的残余应力产生释放,同时船舶结构还承受着不断变化的波浪载荷,所以在估算FPSO等船舶结构典型焊接接头的疲劳强度时,需考虑残余应力释放的影响.该文通过有限元方法分析了在任意变幅循环载荷下,疲劳热点处的残余应力释放的规律,归纳出残余应力释放的大小与初始残余应力和外载荷之间的关系公式.然后,利用此公式对改进的疲劳估算公式进行修正,并且利用修正后的公式估算不同预载荷下典型焊接接头的疲劳强度,结果与试验结果棚符合.利用修正的改进公式可以更合理地对典型焊接接头在任意变幅循环载荷下的疲劳强度进行设计,同时也合理地解释了疲劳试验中以往不能被理解的结果. 相似文献
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The problem with fatigue lifetime estimation of explosive cladded transition joints under random loading conditions has been described. The paper presents the fatigue test results performed for the random state of tension-compression under a generated spectrum according to the Pierson-Moskowitz model. The obtained spectrum has a non-Gaussian characteristic. The tested material consists out of a transition joint clad with four layers of aluminium alloy A5083, A1050, Titanium Grade 1 and steel Grade D. The material has been tested for the existence of residual stresses after the welding process with the hole drilling method. The welding process has been also simulated with ANSYS and the residual stresses have been generated for the Goldak volumetric distribution. The obtained values of residual stresses comprise to the values of real tests performed for the hole drilling method. The information about the residual stress values have been taken into account in the process of fatigue lifetime estimation in the form of non-zero mean stresses compensation inside the clad. The fatigue life has been calculated with the use of the frequency domain method. The Goodman mean stress compensation model has been used in the process of residual stress compensation. The non-gaussianity has been compensated with the use of the Bracessi formula. The obtained fatigue life assessment results have been compared with stand test results. The calculated results are within the scatter area of 3, but individual scatter values have been calculated for calculated series. 相似文献
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焊接残余应力会对结构的力学特性带来不利的影响,而超声冲击能较有效地消除大型焊接结构残余拉应力,起到大幅增加结构疲劳强度的作用。该文首先采用热弹塑性方法对超声冲击前的高强钢平板焊接残余应力进行分析,然后采用瞬态动力学方法对焊接残余应力的超声冲击消除进行三维仿真研究,最后对超声冲击前后残余应力的数值计算结果与试验结果进行对比分析研究。由分析结果可知:超声冲击前高强钢平板焊缝附近存在较大的残余拉应力,呈双峰分布;超声冲击后较大的残余拉应力转化为残余压应力;数值模拟结果与试验结果相一致。并且,平板厚度方向的应力经过超声冲击后表现为应力的均匀化。文中研究结果可为高强钢大型焊接结构超声冲击消除残余应力进行合理评估和后续进行相关力学特性研究提供理论基础和技术支撑。 相似文献
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Residual stresses existing in a multi-pass butt joint with a thickness of 70 mm, using a flux-cored arc welding process, were measured by an inherent strain method (ISM). Since such a thick plate before welding contains a large amount of initial residual stresses (−300 to +100 MPa), the initial stresses were integrated with conventional ISM in order to determine the total residual stresses in a welded joint. Two methods named as initial stress integrated ISM and initial inherent strain integrated ISM were suggested for the consideration of the initial stress distributions through the thickness of base plates. The results show that there is a significant difference between the integrated ISM with initial stresses or initial inherent strain and the conventional ISM without initial stresses. The residual stresses measured by any of the initial stress integrated ISM and initial inherent strain integrated ISM agreed well with the neutron diffraction measurement. Thus, the proposed initial stress integrated ISM is a proper destructive measurement method in the case of thick weld joints. 相似文献
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钛合金具有高强耐蚀、易焊等优质性能,广泛用于潜艇、深潜器等潜水器的受力构件及耐压耐蚀壳体。在焊接过程中,会不可避免的产生焊接残余应力,较大的焊接残余应力会影响焊接结构的安全性能,而焊后热处理能够有效减少焊接残余应力。本文首先采用数值模拟的方法对TC4对接焊平板热处理前后的残余应力进行计算,通过与试验结果进行对比研究,验证有限元数值模拟的合理性;然后采用该数值模拟方法研究Ti80对接焊平板多层多道焊的整个焊接过程以及焊后热处理方法。结果表明,焊后Ti80对接焊平板表面具有较大横向和纵向残余拉应力,通过热处理工艺后,残余拉应力得到明显降低。因此,通过焊后热处理方法可以在很大程度上降低对焊接结构力学性能可能产生的不利影响的残余拉应力。 相似文献
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在进行大型结构焊接变形有限元分析时,为了固定整体结构刚体位移必须施加不少于6个自由度的约束,但对于自由状态下的结构而言,如何施加这6个最少约束是非常的困难,长期以来是困扰研究人员的难题,也是焊接结构有限元分析在工业现场应用的一个瓶颈。所谓惯性释放法就是可以在不加约束的情况下模拟自由结构的变形。该文将在航海航空领域得到广泛应用的惯性释放法引入大型焊接结构变形分析,解决了自由状态下结构必须施加约束的问题。首先以典型的对接接头为例,比较了两种不同的约束方法之间的差别。然后通过一个典型的船体焊接变形预测的实例,验证了惯性释放法在大型结构中应用的可行性,为焊接结构变形分析在工业生产中广泛应用提供了一个有效的方法。 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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Sara Y. Kenno Sreekanta Das John B. Kennedy Ronald B. Rogge Michael Gharghouri 《Marine Structures》2010,23(3):263-273
This paper provides an in-depth study of residual stress distributions found in stiffened steel plate structures, such as those typically used in ship hulls. The effect of stiffener spacing on the distribution of residual stress components was studied. The welding heat input was also varied between high and moderate to study the effect of heat input level on residual stress distributions. Four specimens, resembling typical stiffened steel plate structures used in ship hulls were built and tested. Steel plates of 9.5 mm thickness were stiffened by welding L127 × 76 × 9.5 steel angles. The test was completed using the neutron diffraction method. The three normal components of residual stress were obtained in this study. It was found that a lower heat input results in higher tensile residual stress and that there exists a critical stiffener spacing somewhere beyond 250 mm that creates a maximum tensile residual stress value near the welded connection. 相似文献