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Encyclopedia > Spring (device)
Helical or coil springs designed for tension

The rate of a spring is the change in the force it exerts, divided by the change in deflection of the spring. That is, it is the gradient of the force versus deflection curve. For an extension or compression spring it has the units of lbf/in, N/mm, or similar. For a torsional spring it has the units of N·m/rad or ft·lbf/degree, for example. The inverse of spring rate is compliance, that is if a spring has a rate of 10 N/mm, it has a compliance of 0.1 mm/N. The stiffness (or rate) of springs in parallel adds, and the compliance of springs in series, adds. Look up Rate in Wiktionary, the free dictionary. ... For other uses, see Force (disambiguation). ... This article or section does not cite any references or sources. ... For other uses, see Gradient (disambiguation). ... In mathematics, the concept of a curve tries to capture the intuitive idea of a geometrical one-dimensional and continuous object. ... Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ... Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume. ... // Mathmatics In mathematics, the term torsion has several meanings, mostly unrelated to each other. ... Newton metre is the unit of moment (torque) in the SI system. ... Some common angles, measured in radians. ... The foot-pound force (symbol: ftÂ·lbf) is an English unit of work or energy. ...

## Contents

Simple non-coiled springs were used throughout human history. In the bronze age more sophisticated spring devices were used, as shown by the spread of tweezers in many cultures. The Greek engineer Ctesibius of Alexandria developed a method for making bronze with spring-like characteristics by producing an alloy of bronze with an increased proportion of tin, and then hardening it by hammering after it is cast. Coiled springs were introduced in the 15th century.[1] Ctesibius or Ktesibios or Tesibius (working 285â€“222 BC) of Alexandria (Greek ÎšÏ„Î·ÏƒÎ¯Î²Î¹Î¿Ï‚) was an inventor and mathematician in ancient Greece. ... Assorted ancient Bronze castings found as part of a cache, probably intended for recycling. ... A compression coil spring A tension coil spring A selection of conical coil springs A Coil spring, also known as a helical spring, is a mechanical device, which is typically used to store energy and subsequently release it, to absorb shock, or to maintain a force between contacting surfaces. ...

## Types

A spiral hair spring
A volute spring. Under compression the coils slide over each other, so affording longer travel.

• Coil spring or helical spring - a spring (made by winding a wire around a cylinder) and the conical spring - these are types of torsion spring, because the wire itself is twisted when the spring is compressed or stretched. These are in turn of two types:
• Tension springs are designed to become longer under load. Their turns are normally touching in the unloaded position, and they have a hook, eye or some other means of attachment at each end.
• Compression springs are designed to become shorter when loaded. Their turns are not touching in the unloaded position, and they need no attachment points.
• A volute spring is a compression spring in the form of a cone so that under compaction the coils are not forced against each other, thus permitting longer travel.
• Spiral spring or 'clock spring' - a spring of the type as used in clocks, galvanometers, and places where electricity must be carried to partially-rotating devices such as steering wheels.

• Belleville washer or Belleville spring - a disc shaped spring commonly used to apply tension to a bolt (and also in the initiation mechanism of pressure-activated landmines).
• Spring washer - used to apply a constant tensile force along the axis of a fastener.
• Torsion spring - any spring designed to be twisted rather than compressed or extended.
• Gas spring - a volume of gas which is compressed.
• Rubber band - a tension spring where energy is stored by stretching the material.

SOME IMAGE TAGS ARE MESSED UP Belleville washer A Belleville washer, also known as a cupped spring washer, is a type of non-flat washer. ... â€œMinefieldâ€ redirects here. ... Assorted washers: flat, split, star and insulated A washer is a thin disk with a hole, usually in the middle. ... A fastener is a hardware device that mechanically joins or affixes two or more objects together. ... This article or section does not adequately cite its references or sources. ... A gas spring is a type of spring which, unlike a typical metal spring, uses a compressed gas, contained in a cylinder and variably compressed by a piston, to provide resistance. ... This article is about the common household item. ...

## Physics

Two springs attached to a wall and a mass. In a situation like this, the two springs can be replaced by one with a spring constant of keq=k1+k2.

Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ...

### Hooke's law

Main article: Hooke's law

Springs that are not stretched or compressed beyond their elastic limit obey Hooke's law, which states that the force with which the spring pushes back is linearly proportional to the distance from its equilibrium length: Hookes law accurately models the physical properties of common mechanical springs for small changes in length. ... The elastic limit is the maximum stress a material can undergo at which all strains are recoverable. ...

$F=-kx,$

where

x is the displacement vector - the distance and direction in which the spring is deformed
F is the resulting force vector - the magnitude and direction of the restoring force the spring exerts
k is the spring constant or force constant of the spring.

### Simple harmonic motion

Main article: Harmonic oscillator

Since force is equal to mass, m, times acceleration, a, the force equation looks like: In classical mechanics, a Harmonic oscillator is a system which, when displaced from its equilibrium position, experiences a restoring force proportional to the displacement according to Hookes law: where is a positive constant. ...

The displacement, x, as a function of time. The amount of time that passes between peaks is called the period.

But acceleration is just the second time derivative of x, so Image File history File links Periodampwave. ... Image File history File links Periodampwave. ... Look up period in Wiktionary, the free dictionary. ... For a non-technical overview of the subject, see Calculus. ...

$- k x = m frac{d^2 x}{dt^2}. ,$

Re-arranging results in a differential equation Visualization of airflow into a duct modelled using the Navier-Stokes equations, a set of partial differential equations. ...

$frac{d^2 x}{dt^2} + frac{k}{m} x = 0, ,$

the solution of which is the sum of a sine and cosine: In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ... In mathematics, the trigonometric functions are functions of an angle, important when studying triangles and modeling periodic phenomena. ...

$x(t) = A sin left( t sqrt{frac{k}{m}} right) + B cos left(t sqrt{frac{k}{m}} right). ,$

The graph of this function is displayed in the image on the right.

## Theory

In classical physics, a spring can be seen as a device that stores potential energy by straining the bonds between the atoms of an elastic material. Classical physics is physics based on principles developed before the rise of quantum theory, usually including the special theory of relativity and general theory of relativity. ... Potential energy can be thought of as energy stored within a physical system. ... Properties For other meanings of Atom, see Atom (disambiguation). ... Elasticity is a branch of physics which studies the properties of elastic materials. ...

Hooke's law of elasticity states that the extension of an elastic rod (its distended length minus its relaxed length) is linearly proportional to its tension, the force used to stretch it. Similarly, the contraction (negative extension) is proportional to the compression (negative tension). Hookes law accurately models the physical properties of common mechanical springs for small changes in length. ... Solid mechanics (also known as the theory of elasticity) is a branch of physics, which governs the response of solid material to applied stress (e. ... Tension is a reaction force applied by a stretched string (rope or a similar object) on the objects which stretch it. ... For other uses, see Force (disambiguation). ... Physical compression is the result of the subjection of a material to compressive stress, resulting in reduction of volume. ...

This law actually holds only approximately, and only when the deformation (extension or contraction) is small compared to the rod's overall length. For deformations beyond the elastic limit, atomic bonds get broken or rearranged, and a spring may snap, buckle, or permanently deform. Many materials have no clearly defined elastic limit, and Hooke's law can not be meaningfully applied to these materials. Tensile strength isthe measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks. ...

Hooke's law is actually a mathematical consequence of the fact that the potential energy of the rod is a minimum when it has its relaxed length. Any smooth function of one variable approximates a quadratic function when examined near enough to its minimum point; and therefore the force — which is the derivative of energy with respect to displacement — will approximate a linear function. f(x) = x2 - x - 2 A quadratic function, in mathematics, is a polynomial function of the form , where . ... For a non-technical overview of the subject, see Calculus. ... A linear function is a mathematical function term of the form: f(x) = m x + c where c is a constant. ...

Contrary to popular belief, springs do not appreciably "creep" or get "tired" with age.[citation needed] Spring steel has a very high resistance to creep under normal loads. Say, in a car engine valve spring typically undergoes about a quarter billion cycles of compression-decompression over engine's life time without noticeable change in length or loss of strength. The sag observed in some older automobiles suspension is usually due to the springs being occasionally compressed beyond their yield point, causing plastic deformation. This can happen when the vehicle hits a large bump or pothole, especially when heavily loaded. Most vehicles will accumulate a number of such impacts over their working life, leading to a lower ride height and eventual bottoming-out of the suspension. Creep is the term used to describe the tendency of a material to move or to deform permanently to relieve stresses. ... Car redirects here. ...

## Uses

The front suspension components of a Ford Model T. Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. ... Metal Slinky Rainbow-colored plastic Slinky A Slinky, or Lazy-Spring, is a coil-shaped toy invented by mechanical engineer Richard James in Philadelphia, Pennsylvania. ... An adult using a Pogo Stick A pogo stick is a device, usually considered a childrens toy, used for hopping up and down. ... A dashpot is a mechanical device, a damper which resists motion via viscous friction. ...

## References

1. ^ Springs How Products Are Made, 14 July 2007.

Results from FactBites:

 Class Definition for Class 267 - SPRING DEVICES (2956 words) Spring device including a compartment or material adapted to contain a fluid to be applied to relatively moving portions of the device to reduce friction therebetween. Device in which one of the diverse springs is a metallic member and another of the springs comprises a fluid containing compartment having a restricted or valved orifice to regulate the flow of fluid into or out of the compartment, and the flow of fluid through the orifice dampens the movement of the metallic spring. Device wherein the panel is composed of a series of spiral springs, arranged with the axes of the spirals parallel to each other and aligned in the direction the load is received, and in which the spiral springs are of the type which receive the load in compression.
 Spring (disambiguation) - Wikipedia, the free encyclopedia (183 words) Spring (concerto) is a violin concerto in The Four Seasons by Antonio Vivaldi. Spring Bunny is the secular name given for the Easter Bunny in the United States. Spring holiday is the secular name given for the Christian holiday of Good Friday and Easter in the United States.
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