Bend radius, which is measured to the inside

curvature In mathematics, curvature is any of several strongly related concepts in geometry that intuitively measure the amount by which a curve deviates from being a straight line or by which a surface deviates from being a plane. If a curve or su ...

, is the minimum

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

one can bend a

pipe Pipe(s), PIPE(S) or piping may refer to: Objects * Pipe (fluid conveyance), a hollow cylinder following certain dimension rules ** Piping, the use of pipes in industry * Smoking pipe ** Tobacco pipe * Half-pipe and quarter pipe, semi-circular ...

tube Tube or tubes may refer to: * ''Tube'' (2003 film), a 2003 Korean film * "Tubes" (Peter Dale), performer on the Soccer AM television show * Tube (band), a Japanese rock band * Tube & Berger, the alias of dance/electronica producers Arndt Rör ...

, sheet,

cable Cable may refer to: Mechanical * Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof * Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...

hose A hose is a flexible hollow tube or pipe designed to carry fluids from one location to another, often from a faucet or hydrant. Early hoses were made of leather, although modern hoses are typically made of rubber, canvas, and helically wound w ...

without kinking it, damaging it, or shortening its life. The ''smaller'' the bend radius, the ''greater'' the material flexibility (as the

radius of curvature In differential geometry, the radius of curvature, , is the reciprocal of the curvature. For a curve, it equals the radius of the circular arc which best approximates the curve at that point. For surfaces, the radius of curvature is the radius ...

''decreases'', the

''increases''). The diagram to the right illustrates a cable with a seven-centimeter bend radius. The ''minimum bend radius'' is the

below which an object such as a

should not be bent.

Fiber optics

The minimum bend radius is of particular importance in the handling of

fiber-optic cable A fiber-optic cable, also known as an optical-fiber cable, is an assembly similar to an electrical cable but containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with p ...

s, which are often used in

telecommunications Telecommunication, often used in its plural form or abbreviated as telecom, is the transmission of information over a distance using electronic means, typically through cables, radio waves, or other communication technologies. These means of ...

. The minimum bending radius will vary with different cable designs. The manufacturer should specify the minimum radius to which the cable may safely be bent during installation and for the long term. The former is somewhat larger than the latter. The minimum bend radius is in general also a function of tensile stresses, ''e.g.,'' during installation, while being bent around a sheave while the fiber or cable is under tension. If no minimum bend radius is specified, one is usually safe in assuming a minimum long-term low-stress radius not less than 15 times the cable diameter, or 2 inches. Besides mechanical destruction, another reason why one should avoid excessive bending of fiber-optic cables is to minimize microbending and macrobending losses. Microbending causes light attenuation induced by deformation of the fiber while macrobending causes the leakage of light through the fiber cladding and this is more likely to happen where the fiber is excessively bent.

Other applications

Strain gauge A strain gauge (also spelled strain gage) is a device used to measure Deformation (mechanics)#Strain, strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an Electrical in ...

s also have a minimum bending radius. This radius is the radius below which the strain gauge will malfunction. For metal tubing, bend radius is to the centerline of tubing, not the exterior.

References

{{FS1037C Cables Fiber optics Plumbing Radii vi:Bán kính cong