残余应力对管线钢韧性断裂的影响

Effect of residual stresses on ductile fracture of pipeline steels

以弹塑性断裂力学理论为基础,应用ABAQUS有限元软件,采用固有应变法引入残余应力,并基于细观塑性损伤模型研究了残余应力对管线钢韧性裂纹扩展阻力曲线的影响.模型中选择了具有不同深浅裂纹的单边缺口弯曲(SENB)试样和DNV推荐准则中用于管线钢断裂评估的单边缺口拉伸(SENT)试样,并对这两种断裂力学试样在大范围屈服条件下的裂纹扩展阻力曲线(CTOD-R曲线)行为进行了对比分析.结果表明,对于深裂纹试样,残余应力降低了韧性裂纹扩展阻力曲线,而浅裂纹试样受残余应力的影响可忽略不计.

Welding residual stress is one of the main concerns for fabrication and operation of steel structural due to its potential effect on structural integrity. This paper focuses on the influence of welding residual stress on ductile crack growth resistance of pipeline steels based on the elastic-plastic fracture mechanics theory and the constitutive models. Residual stresses were introduced into the model by using the so-called eigenstrain method. The complete Gurson model has been employed to calculate the ductile crack growth resistance based on the ABAQUS finite element software. The ductile crack growth resistance curves( CTOD-R curve) at large yielding conditions were numerically calculated and analyzed using the single edge notched bending( SENB) specimens and the single notched tension( SENT) specimens. Results show that residual stresses reduce the ductile crack growth resistance for deep-cracked specimens.However,for the shallow-cracked specimens,the effect of residual stress on ductile crack growth resistance can be ignored.