A post-buckling analysis is a continuation of a nonlinear buckling analysis. After a load reaches its buckling value, the load value may remain unchanged or it may decrease, while the deformation continues to increase. For some problems, after a certain amount of deformation, the structure may start to take more loading to keep deformation increasing, and a second buckling can occur. The cycle may even repeat several times.

Because the post-buckling stage is unstable, special techniques must be used. Nonlinear stabilization can help with local and global buckling, and the arc-length method is useful for global buckling. For more information, see Unstable Structures.

Nonlinear stabilization analysis is more straightforward for a post-buckling analysis. Because the buckling load is unknown at the beginning of an analysis, you can do perform a nonlinear analysis as usual using automatic time stepping. When the buckling load is reached or a convergence problem occurs, you can activate stabilization during a multiframe restart and continue the analysis. If the deformation becomes stable later, you can deactivate stabilization until the next buckling occurs.

If only local buckling exists, the total load could still increase when buckling occurs because the total loading is distributed differently. For these cases, nonlinear stabilization is the only applicable technique.

Because nonlinear stabilization cannot detect the negative slope of a load-vs.-displacement curve, it may yield less accurate results for history-dependent materials, and the maximum loads (buckling loads) may not be obvious. For such cases, use the arc-length method.