A circular cylinder made of bare 2024-T3 aluminum alloy is stiffened inside with five Z-section rings. Its ends are closed with thick aluminum bulkheads. A riveted L section exists between the top plate and the top ring and the bottom plate and bottom ring.

The cylinder is subjected to a differential external pressure. The pressure causes a local buckling phenomenon characterized by buckling of the skin between stiffening rings, leading eventually to collapse. The buckling pressure, buckling and collapse pattern, number of waves into which the cylinder buckled, and load-displacement curve are examined and compared to the reference results.

The following table shows the dimensions of the cylinder, ring spacing, and the thicknesses of both cylinder and Z-section rings. The dimensions chosen are based on the reference model.