AskDefine | Define deform

Dictionary Definition

deform

Verb

1 make formless; "the heat deformed the plastic sculpture" [ant: form]
2 twist and press out of shape [syn: contort, distort, wring]
3 cause (a plastic object) to assume a crooked or angular form; "bend the rod"; "twist the dough into a braid"; "the strong man could turn an iron bar" [syn: flex, bend, twist, turn] [ant: unbend]
4 become misshapen; "The sidewalk deformed during the earthquake"
5 alter the shape of (something) by stress; "His body was deformed by leprosy" [syn: distort, strain]
6 assume a different shape or form [syn: change shape, change form]

User Contributed Dictionary

English

Etymology

Middle English, from Old French or Latin; Old French deformer, from Latin deformare, from de- + formare (to form), from forma (form).

Verb

  1. To spoil the form of.
  2. To spoil the looks of; to disfigure; as, a face deformed by bitterness.
  3. To mar the character of; as, a marriage deformed by jealousy.
  4. To alter the shape of by stress.
  5. To become misshapen or changed in shape.

Synonyms

Translations

To spoil the form of
To spoil the looks of; to disfigure
To mar the character of
To alter the shape of by stress
To become misshapen or changed in shape

Usage notes

Deform, distort, contort, warp means to mar or spoil by or as if by twisting. Deform may imply a change of shape through stress, injury, or some accident of growth; as, his face was deformed by hatred. Distort and contort both imply a wrenching from the natural, normal, or justly proportioned, but contort suggests a more involved twisting and a more grotesque and painful result; as, the odd camera angle distorts the figure in the photograph, disease had painfully contorted her body. Warp indicates physically an uneven shrinking that bends or twists out of a flat plane; as, warped floorboards.

Derived terms

Extensive Definition

In engineering mechanics, deformation is a change in shape due to an applied force. This can be a result of tensile (pulling) forces, compressive (pushing) forces, shear, bending or torsion (twisting). Deformation is often described in terms of strain.
In the figure it can be seen that the compressive loading (indicated by the arrow) has caused deformation in the cylinder so that the original shape (dashed lines) has changed (deformed) into one with bulging sides. The sides bulge because the material, although strong enough to not crack or otherwise fail, is not strong enough to support the load without change, thus the material is forced out laterally. Deformation may be temporary, as a spring returns to its original length when tension is removed, or permanent as when an object is irreversibly bent or broken.
The concept of a rigid body can be applied if the deformation is negligible.

Types of deformation

Depending on the type of material, size and geometry of the object, and the forces applied, various types of deformation may result. The image to the right shows the engineering stress vs. strain diagram for a typical ductile material such as steel.

Elastic deformation

This type of deformation is reversible. Once the forces are no longer applied, the object returns to its original shape. Soft thermoplastics and metals have moderate elastic deformation ranges while ceramics, crystals, and hard thermosetting plastics undergo almost no elastic deformation. Elastic deformation is governed by Hooke's law which states:
\sigma=E\epsilon\,\!
Where \sigma is the applied stress, E is a material constant called Young's modulus, and \epsilon is the resulting strain. This relationship only applies in the elastic range and indicates that the slope of the stress vs. strain curve can be used to find Young's modulus. Engineers often use this calculation in tensile tests. The elastic range ends when the material reaches its yield strength. At this point plastic deformation begins.

Plastic deformation

This type of deformation is not reversible. However, an object in the plastic deformation range will first have undergone elastic deformation, which is reversible, so the object will return part way to its original shape. Soft thermoplastics have a rather large plastic deformation range as do ductile metals such as copper, silver, and gold. Steel does, too, but not iron. Hard thermosetting plastics, rubber, crystals, and ceramics have minimal plastic deformation ranges. One material with a large plastic deformation range is wet chewing gum, which can be stretched dozens of times its original length.
Under tensile stress plastic deformation is characterized by a strain hardening region and a necking region and finally, fracture (also called rupture). During strain hardening the material becomes stronger through the movement of atomic dislocations. The necking phase is indicated by a reduction in cross-sectional area of the specimen. Necking begins after the Ultimate Strength is reached. During necking, the material can no longer withstand the maximum stress and the strain in the specimen rapidly increases. Plastic deformation ends with the fracture of the material.

Metal fatigue

Another deformation mechanism is metal fatigue, which occurs primarily in ductile metals. It was originally thought that a material deformed only within the elastic range returned completely to its original state once the forces were removed. However, faults are introduced at the molecular level with each deformation. After many deformations, cracks will begin to appear, followed soon after by a fracture, with no apparent plastic deformation in between. Depending on the material, shape, and how close to the elastic limit it is deformed, failure may require thousands, millions, billions, or trillions of deformations.
Metal fatigue has been a major cause of aircraft failure, such as the De Havilland Comet, especially before the process was well understood. There are two ways to determine when a part is in danger of metal fatigue; either predict when failure will occur due to the material/force/shape/iteration combination, and replace the vulnerable materials before this occurs, or perform inspections to detect the microscopic cracks and perform replacement once they occur. Selection of materials which are not likely to suffer from metal fatigue during the life of the product is the best solution, but not always possible. Avoiding shapes with sharp corners limits metal fatigue by reducing stress concentrations, but does not eliminate it.

Fracture

This type of deformation is also not reversible. A break occurs after the material has reached the end of the elastic, and then plastic, deformation ranges. At this point forces accumulate until they are sufficient to cause a fracture. All materials will eventually fracture, if sufficient forces are applied.

Misconceptions

A popular misconception is that all materials that bend are "weak" and all those which don't are "strong". In reality, many materials which undergo large elastic and plastic deformations, such as steel, are able to absorb stresses which would cause brittle materials, such as glass, with minimal elastic and plastic deformation ranges, to break. There is even a parable to describe this observation (paraphrased below):
"The mighty oak stands strong and firm before the wind, while the willow yields to the slightest breeze. However, in the strongest storm, the oak will break while the willow will bend, and thus survive. So, in the end, which is the stronger of the two?"
deform in Azerbaijani: Deformasiya
deform in Bulgarian: Деформация
deform in Czech: Deformace
deform in German: Verformung
deform in Estonian: Deformatsioon
deform in Spanish: Deformación
deform in Esperanto: Deformiĝo
deform in French: Déformation des matériaux
deform in Galician: Deformación
deform in Italian: Deformazione
deform in Latvian: Deformācija
deform in Lithuanian: Kūno deformacija
deform in Norwegian: Deformasjon
deform in Portuguese: Deformação
deform in Russian: Деформация
deform in Simple English: Deformation
deform in Swedish: Deformation
deform in Turkish: Şekil değiştirme
deform in Ukrainian: Деформація
deform in Chinese: 形變

Synonyms, Antonyms and Related Words

accommodate, adapt, adjust, alter, ameliorate, batter, better, blemish, blur, break up, change, check, cicatrize, confuse, contort, convert, crack, craze, cripple, damage, deface, denature, disfigure, disorder, disproportion, distort, diversify, fit, flaw, fog up, impair, improve, injure, jumble, kink, maim, mangle, mar, meliorate, mess up, misshape, mitigate, modify, modulate, muddle, mutate, mutilate, obfuscate, obscure, overthrow, qualify, re-create, realign, rebuild, reconstruct, redesign, refit, reform, remake, renew, reshape, restructure, revamp, revive, ring the changes, scab, scar, scarify, screw up, shift the scene, shuffle the cards, split, spoil, squinch, subvert, torture, truncate, turn the scale, turn the tables, turn the tide, turn upside down, twist, unform, unshape, vary, warp, wind, work a change, worsen
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