3. Instability and post-critical behavior of perfect bars, plates and shells

To fully understand the sensitivity of shells to imperfections, it is useful to note the significant difference in postcritical behavior of columns, plates and shells by comparing equilibrium trajectories for these three types of structural elements. Equilibrium trajectories for a perfectly straight column, a perfectly flat plate supported along its four edges, and a perfect cylindrical shell under longitudinal compression are represented by continuous and intersecting lines in figures 8 a, 8 b and 8...