Numerical study on influence of rupture strain on crack driving force of welded joints with damage

Fully coupled strain and damage elastic-plastic finite element analysis was carried for three-point bend specimens with welded joint containing damage, and the influence of rupture stain ε_fB, that is, one of damage parameters of base metal on crack driving force J-integral was discussed in detail. The results show that the rupture strain of base metal has large effects on the fracture behavior of crack in weld metal. If mechanical parameters of weld metal are kept constant, the plastic strain along the ligament and the crack driving force J-integral increase both with the decrease of the rupture strain of base metal, the increase of damage rate and the enlarge of damaged zone subsequently for all kinds of welded joint with different strength matching ratio. However, with the decrease of strength matching ratio (viz. the increasing of the strength of base metal), or with the increase of weld width, the effect of the rupture strain of base metal on the J-integral is weaken gradually, and may vanish entirely when the weld metal parameter 2H/a is more than 0.6 in this investigation, the value of the J-integral calculated from welded joint specimens is equal to that from full weld metal specimen.