Numerical Simulations of Ductile Crack Growth on Circumferentially Flawed Pipes under Combined Load Conditions

Abstract

For certain applications, pipelines may be submitted to biaxial loading situations. In these cases, it is not clear the influence of the biaxiality on the fracture mechanics behavior of cracked pipelines. For further understanding of biaxial loading effects, this work presents a numerical simulation of ductile tearing in a circumferentially surface cracked pipe under combined loading conditions using the computational cell methodology. The model was adjusted with experimental results obtained in laboratory using single edge cracked under tension (SENT) specimens. These specimens appear as a better alternative to conventional fracture specimens to characterize fracture toughness of circumferentially cracked pipes. The negligible effect of biaxial loadings on resistance curves was demonstrated. To guarantee the similarities of stress and strains fields between SENT specimens and cracked pipes subjected to internal pressure plus bending, a constraint study using the J-Q methodology and the h parameter was used. The constraint study gives information about the characteristics of the crack-tip conditions.