Non-standard stabilization of the post-buckling path for elastic–plastic cylindrical shells under combined state of loadings

• Stabilization of the unstable path can be achieved by application of active or passive axial loads or by application of both.
• The problem of stabilization is formulated as a non-standard optimization problem.
• The active force stabilizes the unstable path for any combination of both loads.
• The passive force stabilizes the unstable path only for thicker structures and larger torque.
• The mixed variant stabilizes the unstable path only for thicker structures and larger torque.

The post-buckling behavior of elastic–plastic cylindrical shells under external pressure and twisting moment is unstable. The effect of stabilization of the post-buckling behavior is in most cases obtained by changing geometry of the structure. In this paper an alternative concept of modification of the post-buckling behavior is applied, namely modification of post-buckling path is achieved by application of additional loadings acting on the structure without changing the shape or sizes of the optimized element. Calculations are performed using ANSYS code for elastic–plastic shells of different length and thickness for the whole range of load from a pure external pressure to a pure twisting moment. It turned out that the active stabilizing force can always stabilize the post-buckling paths whereas the passive and ‘mixed’ variant of stabilizing loads are able to stabilize the post-buckling paths only for thicker elastic–plastic shells and for limited states of loading.