Honeycomb structure of the honeycomb remains roughly constant. Once a certain strain is reached, the material will begin to undergo densification as further compression pushes the cell walls together. Out of-plane loading: Under out-of-plane loading, the out-of-plane Young’s modulus of a regular hexagonal honeycombs is proportional to the relative density of the honeycomb. The elastic buckling stress is proportional to (t/L) while the plastic buckling stress is proportional to (t/L). The shape of the honeycomb cell is often varied to meet different engineering applications. Shapes that are commonly used besides the regular hexagonal cell include triangular cells, square cells, and circular-cored hexagonal
Honeycomb (geometry) polyhedral cells, and having all vertices the same (i.e., the group of [isometries of 3-space that preserve the tiling] is "transitive on vertices"). There are 28 convex examples in Euclidean 3-space, also called the Archimedean honeycombs. A honeycomb is called regular if the group of isometries preserving the tiling acts transitively on flags, where a flag is a vertex lying on an edge lying on a face lying on a cell. Every regular honeycomb is automatically uniform. However, there is just one regular honeycomb in Euclidean 3-space, the cubic honeycomb. Two are "quasiregular" (made from two types of regular cells):