Honeycomb structure
Honeycomb materials are widely used where flat or slightly curved surfaces are needed and their high specific strength is valuable.
They can also be found in many other fields, from packaging materials in the form of paper-based honeycomb cardboard, to sporting goods like skis and snowboards.
The first man-made honeycomb, according to Greek mythology, is said to have been manufactured by Daedalus from gold by lost wax casting more than 3000 years ago.
[2] Marcus Varro reports that the Greek geometers Euclid and Zenodorus found that the hexagon shape makes most efficient use of space and building materials.
The interior ribbing and hidden chambers in the dome of the Pantheon in Rome is an early example of a honeycomb structure.
[4] Robert Hooke discovers in 1665 that the natural cellular structure of cork is similar to the hexagonal honeybee comb.
[6] The first paper honeycomb structures might have been made by the Chinese 2000 years ago for ornaments, but no reference for this has been found.
Paper honeycombs and the expansion production process has been invented in Halle/Saale in Germany by Hans Heilbrun in 1901[7] for decorative applications.
[8] For the same purpose, as foundation sheets to harvest more honey, a honeycomb moulding process using a paper paste glue mixture had been patented in 1878.
[10] He described in detail his concept to replace the fabric covered aircraft structures by metal sheets and reasoned that a metal sheet can also be loaded in compression if it is supported at very small intervals by arranging side by side a series of square or rectangular cells or triangular or hexagonal hollow bodies.
The problem of bonding a continuous skin to cellular cores led Junkers later to the open corrugated structure, which could be riveted or welded together.
[11] In 1934 Edward G. Budd patented a welded steel honeycomb sandwich panel from corrugated metal sheets and Claude Dornier aimed 1937 to solve the core-skin bonding problem by rolling or pressing a skin which is in a plastic state into the core cell walls.
[13] The North American XB-70 Valkyrie made extensive use of stainless steel honeycomb panels using a brazing process they developed.
For decorative applications the expanded honeycomb production reached a remarkable degree of automation in the first decade of the 20th century.
Early wind tunnels used them with no screens; unfortunately, this method introduced high turbulence intensity in the test section.
Two mechanics pose near the entrance end of the actual tunnel, where air was pulled into the test section through a honeycomb arrangement to smooth the flow.
[28] In combination with two skins applied on the honeycomb, the structure offers a sandwich panel with excellent rigidity at minimal weight.
[29][30] Under high enough compressive load, the honeycomb reaches a critical stress and fails due to one of the following mechanisms – elastic buckling, plastic yielding, or brittle crushing.
