SPHERICAL SHELLS LIKE HEXAGONS. CYLINDERS PREFER DIAMONDS - 1.

Describes the initial postbuckling behavior of cylindrical shells under axial compression. The thesis is that, out of a single infinity of possible buckling configurations which all correspond to diamond-shaped patterns, the square diamond pattern dominates. It is not claimed that this pattern will be seen under all circumstances; if no substantial bias is present in either the initial imperfections or initial conditions, a natural selection mechanism exists which favors the square diamond configuration. A multiple scale technique is used to describe both the dynamic interaction and evolution of competing diamond patterns and the propagation of spatial inhomogeneities. Stability analysis on the resulting differential equation system lends support to the stated thesis. In addition, some initial numerical studies are presented. Part 2 will be devoted to more extensive numerical experiments.