fuller (weapon)

Enlarge picture
Prussian bayonet, with a prominent fuller
A Fuller is a rounded or beveled groove on the flat side of a blade, such as a sword, knife, or bayonet (shown). Although 19th century romantic fancy referred to them as "blood grooves", their purpose is to lighten the blade, rather than to allow blood to flow from a stabbed person.

Some speculate that this design feature makes a weapon easier to withdraw after a stabbing attack by allowing air into the wound it produces, but no evidence has demonstrated any resisting suction effect. Many blades use fullers even when they are so short that the physical effect is negligible; in this case, the purpose may be to make the weapon resemble larger blades.

Physics

Figure 2. Internal forces and the cross-sectional stress distribution due to bending.
The basic design principle is that bending causes more stress in material near the edge or back of the blade than material in the middle, due to leverage. The diagram at left shows stress distribution in an ideal blade with a rectangular section, with only a small amount of shear stress present at the neutral axis. Fullers remove material from near this neutral axis, which is closer to the blade's spine if only one edge is sharpened (see photo above). This yields stiffer blades of a given weight, or lighter blades of a given stiffness. The same principle is taken to an extreme in the I-shaped cross sections of most steel beams. Some even contend that this concept was borrowed into architecture from weapons design [1].

Japanese blades

In Japanese bladesmithing, fullers have a rich tradition and terminology, enough that there are separate terminologies for the top (hi, usually pronounced as bi when used as a successive word) and bottom (tome) ends of the feature. A listing follows:
  • Hi
  • Bo-bi: A continuous straight groove of notable width, known as katana-bi on tanto. With soe-bi, a secondary narrow groove follows the inner straight length of the main one. With tsure-bi, the secondary is similar but continues beyond the straight length.
  • Futasuji-bi: Two parallel grooves.
  • Shobu-bi: A groove shaped like the leaf of an iris plant.
  • Naginata-bi: A miniature bo-bi whose top is oriented opposite from the blade's, and usually accompanied by a soe-bi. Seen primarily on naginatas.
  • Kuichigai-bi: Two thin grooves that run the top half of the blade; the bottom half is denoted by the outer groove stopping halfway while the inner one expands to fill the width.
  • Koshi-bi: A short rounded-top groove found near the bottom of a blade, near to the tang.
  • Tome
  • Kaki-toshi: The groove runs all the way down to the end of the tang.
  • Kaki-nagashi: The groove tapers to a pointed end halfway down the tang.
  • Kaku-dome: The groove stops as a square end within 3 cm of the tang's upper end.
  • Maru-dome: Similar to the kaku, except with a rounded-end.

The kukri

The Nepali kukri has a terminology of its own, including the "aunlo bal" (finger of strength/force/energy), a relatively deep and narrow fuller near the spine of the blade, which runs (at most) between the handle and the corner of the blade, and the "chirra", which may refer either to shallow fullers in the belly of the blade or a hollow grind of the edge, and of which two or three may be used on each side of the blade [2].

References

A sword is a long-edged piece of metal, used as a cutting and/or thrusting weapon in many civilizations throughout the world. The word sword comes from the Old English , which cognates to Old High German swert, Middle Dutch swaert, Old Norse
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knife is a sharp-edged (single or double edged) instrument consisting of a thin blade used for cutting and fitted with a handle. The knife can be used as a tool or a weapon.
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bayonet (from French baïonnette) is a knife- or dagger-shaped weapon designed to fit on or over the muzzle of a rifle barrel or similar weapon. It is a close-combat or last-resort weapon.
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A blade is the flat part of a tool, weapon, or machine (such as a fan) that normally has a cutting edge and/or pointed end typically made of a metal, most recently, steel intentionally used to cut, stab, slice, throw, thrust, position and/or place (an example of this is
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This article is about structural behavior. For other meanings see Bending (disambiguation).

In engineering mechanics, bending (also known as flexure
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Stress is a measure of force per unit area within a body. It is a body's internal distribution of force per area that reacts to external applied loads. Stress is often broken down into its shear and normal components as these have unique physical significance.
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lever (from French lever, "to raise", c.f. a levant) is a rigid object that is used with an appropriate fulcrum or pivot point to multiply the mechanical force that can be applied to another object.
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Stiffness is the resistance of an elastic body to deflection or deformation by an applied force. It is an extensive material property.

Definition

The stiffness k of a body that deflects a distance δ under an applied force P is


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beam is a structural element that carries load primarily in bending (flexure). Beams generally carry vertical gravitational forces but can also be used to carry horizontal loads (i.e. loads due to an earthquake or wind).
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Nihontō (日本刀:にほんとう nihontō
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Tanto may refer to several things. Please see:
  • Tantō - A Japanese weapon
  • Tanto, Stockholm - A district of Stockholm, Sweden.
See also: Tonto.

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leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat (laminar) and thin, to expose the cells containing chloroplast (chlorenchyma tissue, a type of parenchyma) to light over a broad area, and to allow light to penetrate
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Iris
L.

Species
See text
Iris is a genus of between 200-300 species of flowering plants with showy flowers which takes its name from the Greek word for a rainbow, referring to the wide variety of flower colors found among the many species.
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Naginata (なぎなた, 薙刀) is a pole weapon that was traditionally used in Japan by members of the samurai class.
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Motto
जननी जन्मभूमिष्च स्वर्गादपि गरीयसी   (Sanskrit)
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The Kukri or Khukuri (Devanāgarī: खुकुरी) is a heavy, curved Nepalese knife used as both tool and weapon.
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The grind of a blade refers to the shape of the cross-section of the blade. It is distinct from the type of blade (e.g., clip point or drop point knife, sabre or cutlass, axe or chisel, etc.), though different tools and blades may have lent their name to a particular grind.
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