Analysis of Main Gas Pipeline Crack Resistance at a Distance from Transverse Weld

The paper presents the results of the analysis of crack resistance of a main gas pipeline linear section at a distance from the transverse butt weld. The calculation is based on the two-parameter fracture criterion previously proposed by the authors, according to which fracture occurs if the effective stress intensity factor (SIF) reaches a critical value (fracture toughness) obtained under conditions of maximum triaxial constraint. In this case, in addition to the normal SIF, the effective SIF includes <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{T}_{\mathbf{xx}^{-}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{T}_{\mathbf{zz}}$</tex>-stresses, which are non-singular terms in the Williams stress expansion. Introduction of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{T}_{\mathbf{xx}}$</tex>-stresses into equation for the effective SIF allows taking into account the constraint along the crack front in the transverse direction, and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{T}_{zz}$</tex>-stresses - in the longitudinal direction. The paper deals with the analysis of main gas pipeline crack resistance with a surface semi-elliptical longitudinal crack using this two-parameter fracture criterion. Numerical calculations were performed in the ANSYS Workbench finite element environment. The graphs of the distribution of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{T}_{\mathbf{xx}^{-}}$</tex> and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\boldsymbol{T}_{\mathbf{zz}}$</tex>-stresses, as well as the normal and effective SIF along the crack front are given. The results of the crack resistance calculation are presented as a dependence of the critical crack depth on the ratio of the crack half-length to its depth