Study On The Collapse Strength Of Thin-walled Octg(Oil Countn Tubular Goods) Exerted By Axial Compressive Force

Tubing and casing(OCTG) were exerted by axial compressive force, external pressure, and interna] pressure while in the oil well. Axial compressive force could result in longitudinal buckling of the OCTG on one aspect, and transverse buckling behavior(collapse strength) changing of the OCTG(especially the thin-walled OCTG) on the other aspect. Therefore, in this paper, the thin-walled OCTG was taken as cylindrical shell, and the buckling equation of the thin-walled OCTG exerted by axial compressive force and external pressure was derived, and based on which the longitudinal buckling behavior and the transverse buckling behavior(transverse buckling configuration and collapse strength included) of the thin-walled OCTG with various edge conditions could be analyzed.On the basis of the thin-walled OCTG buckling equation, the thin-walled OCTG was taken as cylindrical shell with two ends pinned, an end fixed and the other free, and both ends fixed respectively, functions of the deflection curve of the cylindrical shell were selected and substituded into the simplified Donnell eight-order diferential equation, though this equation being converted into the critical stress expression, the longitudinal buckling critical stress and the transverse buckling configuration and transverse buckling critical stress(collapse strength) could be obtained by the means of minimization.Finally?in terms of different values of the half waveleghths of the deflection in the circumferential and axial directions, the transverse buckling configurations of the cylindrical shell with two ends pinned, an end fixed and the other free, and both ends fixed were dicussed respectively.