降低FPSO含裂纹焊接结构应力集中系数的焊接修理形状的研究

对焊缝处出现的裂纹进行焊接修理,以阻止其进一步的扩展,这一方法能够有效地延长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,要谨慎选取焊接修理所采用的形状和尺寸,避免产生过高的应力集中.在本文中,研究了不同几何形状和尺寸的二维焊接修理切口的应力集中系数,如抛物线型和椭圆型等,并与相类似尺寸的U型切口进行了比较.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.将椭圆型的焊接修理形状用于补板与纵骨的连接处,以计算进行焊接修理消除裂纹后结构的最大主应力.结果表明,在消除产生的裂纹以后,含焊接修理切口的结构可以恢复到初始的应力状态.

Investigation of Repair Profiles on Minimizing the SCF of Cracked 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 of welded structures in FPSOs. In this paper, two dimensional repair profiles in different geometries, such as elliptical and parabola profiles with different sizes are investigated.SCFs obtained from these repair profiles are compared with corresponding U-shaped profiles. When the half surface width is longer than the depth, the elliptical repair profiles are preferable. One of the repair profiles (E_D4R6) is applied to the connection of a lug plate and the longitudinal stiffener,to calculate the maximum principal stress after crack removal.It can be found that when the crack is removed, the original stress status can be resumed.