Abstract: Because of the presence of initial geometric defects, the analysis of plastic-matrix steel composite pipe (PSP) buckling is complicated for nonlinear and large deformation was involved. In this paper, numerical simulations were carried out using FEA code ANSYS 10. 0 to study the mechanical response of PSP under external pressure, based on the eigenvalue and nonlinear method. the critical buckling pressures and buckling mode shapes of PSP were obtained. the critical buckling pressures analyzed by eigenvalue and nonlinear method are 0 .97 MPa and 0. 83 MPa, respectively. By analyzing the influences of boundary conditions and initial imperfection on the stability of external pressure, the reladons of the critical buckling pressure and ripple number versus the length-diameter ratio were obtained.

Key words: plastic-matrix steel composite pipe, external pressure buckling, numerical simulation;eigenvalue method;nonlinear method