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断裂应变对含损伤焊接接头裂纹扩展驱动力影响的数值

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

  • 摘要: 利用弹塑性损伤-应变耦合有限元方法,对含有损伤的焊接接头三点弯曲裂纹试样进行了模拟计算,讨论了母材区的断裂应变εfB的变化对焊缝区裂纹的扩展驱动力J积分的影响规律。结果表明,焊缝中裂纹的断裂行为受到焊缝两侧母材断裂应变的明显影响。对于无论何种强度匹配的接头,在焊缝区各项力学性能参数保持不变的条件下,随着母材区断裂应变的减小,损伤率的增加,损伤区的扩大,焊缝中裂纹韧带区塑性应变及裂纹扩展驱动力J积分均有明显的提高;随着接头强度匹配比M的降低(即母材屈服强度的升高),母材区断裂应变的变化对J积分的影响作用逐渐减弱;随着焊缝宽度的逐渐增加,母材断裂应变的变化对J积分的影响作用逐渐减弱,焊接接头试样的计算J积分值逐渐趋向于全焊缝材料试样计算得到的J积分值;当焊缝宽度增加到2H/a约为0.6时,母材断裂应变的变化对焊缝区裂纹扩展驱动力J积分的影响作用完全消失。

     

    Abstract: 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 εfB, 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.

     

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