A Hertzian cone is the

cone A cone is a three-dimensional geometric shape that tapers smoothly from a flat base (frequently, though not necessarily, circular) to a point called the apex or vertex. A cone is formed by a set of line segments, half-lines, or lines con ...

produced when an object passes through a

solid Solid is one of the four fundamental states of matter (the others being liquid, gas, and plasma). The molecules in a solid are closely packed together and contain the least amount of kinetic energy. A solid is characterized by structur ...

, 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. Br ...

amorphous In condensed matter physics and materials science, an amorphous solid (or non-crystalline solid, glassy solid) is a solid that lacks the long-range order that is characteristic of a crystal. Etymology The term comes from the Greek language, Gr ...

, or

cryptocrystal Cryptocrystalline is a rock texture made up of such minute crystals that its crystalline nature is only vaguely revealed even microscopically in thin section by transmitted polarized light. Among the sedimentary rocks, chert and flint are cryptocr ...

line 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 (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the centra ...

tool stone A tool is an object that can extend an individual's ability to modify features of the surrounding environment or help them accomplish a particular task. Although many animals use simple tools, only human beings, whose use of stone tools dates bac ...

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. The unit ...

, 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 A chatter mark is one or, more commonly, a series of wedge shaped marks left by chipping of a bedrock surface by rock fragments carried in the base of a glacier (glacial plucking). Marks tend to be crescent-shaped and oriented at right angles t ...

" made on smoothed bedrock by

glacial ice A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

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 crater-forming body, or to one that explodes in the atmosphere. It can be a ...

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 ranged weapon munitions such as bullets, unguided bombs, rockets or the like; the science or art of designing a ...

, 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