A Hertzian cone is the

cone In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the '' apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines ...

produced when an object passes through a

solid Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...

, such as a bullet through glass. More technically, it is a cone of force that propagates through a

brittle A material is brittle if, when subjected to stress, it fractures with little elastic deformation and without significant plastic deformation. Brittle materials absorb relatively little energy prior to fracture, even those of high strength. ...

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid) is a solid that lacks the long-range order that is a characteristic of a crystal. The terms "glass" and "glassy solid" are sometimes used synonymousl ...

, or cryptocrystalline solid material from a point of impact. This force eventually removes a full or partial cone in the material. This is the physical principle that explains the form and characteristics of the flakes removed from a

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...

tool stone In archaeology, a tool stone is a type of stone that is used to manufacture stone tools, or tools that use stone as raw material. Generally speaking, tools that require a sharp edge are made using cryptocrystalline materials that fracture i ...

during the process of

lithic reduction In archaeology, in particular of the Stone Age, lithic reduction is the process of fashioning stones or rocks from their natural state into tools or weapons by removing some parts. It has been intensely studied and many archaeological industrie ...

. This phenomenon is named after the German physicist

Heinrich Rudolf Hertz Heinrich Rudolf Hertz (; ; 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell's equations of electromagnetism. Biography Heinric ...

, who first described this type of wave-front propagation through various media. Although it might not be agreed by all, natural phenomena which have been grouped with the Hertzian cone phenomena include the crescentic " chatter marks" made on smoothed bedrock by glacial ice dragging along boulders at its base, the numerous crescentic impact marks sometimes seen on pebbles and cobbles, and the shatter cones found at

bolide A bolide is normally taken to mean an exceptionally bright meteor, but the term is subject to more than one definition, according to context. It may refer to any large Impact crater, crater-forming body, or to one that explodes in the atmosphere. ...

impact sites. James Byous, working independently (at privately funded Dowd Research, Savannah, Georgia USA) has made a protracted study of Hertzian cones. Some of his work may be found via sharing points or directly at Dowd Research. He has produced a comprehensive glossary on Hertzian fractures and related terms. A Hertzian cone is often 104 degrees when created by an indenter. Smaller cones may be produced due to lack of size of the material, or irregularities in the structure of the material. However, in

ballistics Ballistics is the field of mechanics concerned with the launching, flight behaviour and impact effects of projectiles, especially weapon munitions such as bullets, unguided bombs, rockets and the like; the science or art of designing and acceler ...

, the faster the projectile the steeper the edges and angle of the cone.

References

{{DEFAULTSORT:Hertzian Cone Materials science Lithics Heinrich Hertz

See also

References