A cylindrical shell due to axial load produces concertina mode or non-axisymmetric mode. 0n the potential to absorb impact energy, the former is better than the later is. The main factor to control the buckling mode of cylindrical shell is its geometrical parameter R/t. However, it is difficult to predict the buckling mode, because to control the shape imperfection and the boundary condition etc. influence it. This study aims to control the progressive buckling modes by use of the boundary conditions that constrain outward or inward deformation. In order to investigate their effect, experiment and FE analysis are carried out. Outward constraints and constrains-free produce non-axisymmetric mode, and inward constraint causes concertina mode.
