Mechanical analysis of semi-elliptical cracks on surface of gas storage injection-production pipe string after buckling
The stress intensity factor KI and J integral of the semi-elliptical crack on the surface of the injection-production pipe string af-ter buckling were studied by using the finite element method.First,since the gas storage injection-production pipe string is a long straight circular pipe structure,the finite element model of the straight pipe with cracks on the outer surface was established to conduct finite ele-ment verification.Then,based on the submodel method,the crack mechanical calculation model after pipe string buckling was estab-lished,and the stress intensity factors KI and J integrals with different crack shape parameters,crack relative depths and axis angles after buckling were calculated,and the effect low of different pitch numbers of pipe string on K1 and J integrals was analyzed.The results show that the finite element method has high accuracy in calculating the stress intensity factor,and the main factors causing the obvious error of the finite element method are the grid size and the number of crack leading edge meshing.After helical buckling of the pipe string,KI and J integral decrese with the increase of shape parameter,and increase with the increase of or crack relative depth;with the increase of the number of buckling pitches of the injection-production pipe string as well as the axial angle,both KI and J integral tend to increase,and the increase rate is the largest when the crack is a circumferential crack.
finite elementinjection-production pipe stringcrackhelical bucklingstress intensity factorJ integral
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