Stability of corrugated expansion bellows: shell and rod models

The problem of stability of corrugated thin-wall expansion bellows under hydrostatic internal load is considered. The bellows is modeled by an elastic rod with equivalent tensile, bending, and shear stiffness. Equations for calculating the critical value of fluid pressure at which the bellows loses stability are analytically derived, using an expression for hydrostatic follower load. The equivalent stiffness of the bellows is determined further from the solution of static problems for the elastic corrugated shell. The numerical solutions of the boundary value problems and the critical values of the pressure are obtained by the finite difference method. Additionally, a computer model of the expansion bellows was developed by ANSYS software, and the bellows stability was analyzed using shell finite elements. Calculations confirm the necessity of accounting for the axial displacement of expansion joint support when determining the critical pressure.