FPSO节点焊趾处的裂纹修理形状研究

对焊缝处出现的裂纹进行修理以阻止其进一步扩展,能够有效地延长FPSO焊接结构的疲劳寿命.考虑到应力集中而造成的疲劳寿命的降低,要谨慎选取修理时所采用的形状和尺寸,避免在修理后产生的表面缺陷处出现过高的应力集中.文中旨在进行三维T型焊接节点焊趾处的裂纹修理分析,为了选取合理的修理切口,首先对不同几何形状和尺寸的二维焊接修理切口,如抛物线型和椭圆型等,进行了应力集中系数的计算,并与相类似尺寸的U型切口的计算结果进行了比较.结果表明,当切口的表面半宽长于其深度时,椭圆型的裂纹修理切口具有更低的应力集中系数.随后,选择应力集中较小的椭圆型和U型切口焊接修理形状,并采用更加精确的三维有限元分析方法进行分析,给出了通过打磨等修理方式消除裂纹后得到的三维表面缺陷的应力集中系数,为工程上焊趾处裂纹的修理提供决策依据.

A study on crack repair profiles of welded details in FPSO

Since higher stress concentration factor(SCF) leads to lower fatigue life,it should be careful to choose the shape and dimensions of weld repair profile to avoid high SCF.In this paper,a study is carried out for the crack repair profiles of welded joints in FPSO.In order to select the correct shape for repair profile,two dimensional repair profiles in different geometries,such as elliptical and parabola profiles with different sizes are investigated first to make comparison of SCFs obtained from these repair profiles with corresponding U-shaped profiles.Results show that when the half surface width is longer than the depth,the elliptical repair profiles are preferable.Then the preferable two dimensional weld repair profiles are selected to calculate SCFs using more refined three dimensional finite element models.The SCFs of weld repair profiles after crack removal are given which could be acted as an important basis for decision making.