Honeycomb Structure - History

History

The hexagonal comb of the honey bee has been admired and wondered about from ancient times. The first man-made honeycomb is said to have been manufactured by Daedalus from gold by lost wax casting more than 3000 years ago. Marcus Varro reports that the Greek geometricians 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.

Galileo Galilei discusses in 1638 the resistance of hollow solids: "Art, and nature even more, makes use of these in thousands of operations in which robustness is increased without adding weight, as is seen in the bones of birds and in many stalks that are light and very resistant to bending and breaking”. Robert Hook discovers in 1665 that the natural cellular structure of cork is similar to the hexagonal honeybee comb. and Charles Darwin states in 1859 that "the comb of the hive-bee, as far as we can see, is absolutely perfect in economizing labour and wax”.

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 for decorative applications. First honeycomb structures from corrugated metal sheets had been proposed for bee keeping in 1890. 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. The three today still used basic honeycomb production techniques: expansion, corrugation and moulding were already developed by 1901 for non-sandwich applications.

Hugo Junkers first explored the idea of a honeycomb core within a laminate structure. He proposed and patented the first honeycomb cores for aircraft application in 1915. 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.

The first use of honeycomb structures for structural applications had been independently proposed for building application and published already in 1914. 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. The first successful structural adhesive bonding of honeycomb sandwich structures was achieved by Norman de Bruyne of Aero Research Limited, who patented an adhesive with the right viscosity to form resin fillets on the honeycomb core in 1938. The North American XB-70 Valkyrie made extensive use of stainless steel honeycomb panels using a brazing process they developed.

A summary of the important developments in the history of honeycomb technology is given below:

• 60 BC Diodorus Siculus reports a golden honeycomb manufactured by Daedalus via lost wax casting.
• 36 BC Marcus Varro reports most efficient use of space and building materials by hexagonal shape.
• 126 The Pantheon was rebuilt in Rome using a honeycomb structure to support its dome.
• 1638 Galileo Galilei discusses hollow solids and their increase of resistance without adding weight.
• 1665 Robert Hook discovers that the natural cellular structure of cork is similar to the hexagonal honeybee comb.
• 1859 Charles Darwin states that the comb of the hive-bee is absolutely perfect in economizing labour and wax.
• 1877 F. H. Küstermann invents a honeycomb moulding process using a paper paste glue mixture.
• 1890 Julius Steigel invents the honeycomb production process from corrugated metal sheets.
• 1901 Hans Heilbrun invents the hexagonal paper honeycombs and the expansion production process.
• 1914 R. Höfler and S. Renyi patent the first use of honeycomb structures for structural applications.
• 1915 Hugo Junkers patents the first honeycomb cores for aircraft application.
• 1931 George Thomson proposes to use decorative expended paper honeycombs for lightweight plasterboard panels.
• 1934 Edward G. Budd patents welded steel honeycomb sandwich panel from corrugated metal sheets.
• 1937 Claude Dornier patents a honeycomb sandwich panel with skins pressed in a plastic state into the core cell walls.
• 1938 Norman de Bruyne patents the structural adhesive bonding of honeycomb sandwich structures.
• 1941 John D. Lincoln proposes the use expanded paper honeycombs for aircraft radomes
• 1948 Roger Steele applies the expansion production process using fiber reinforced composite sheets.
• 1969 Boeing 747 uses extensively fire-resistant honeycombs from Hexcel Composites using DuPont's Nomex aramid fiber paper.
• 1980's Thermoplastic honeycombs produced by extrusion processes are introduced.