Deformation
Deformation can refer to:
- Deformation (mechanics), such changes considered and analyzed as displacements of continuum bodies.
See also
Deformation (meteorology)
Deformation is the rate of change of shape of fluid bodies. Meteorologically, this quantity is very important in the formation of atmospheric fronts, in the explanation of cloud shapes, and in the diffusion of materials and properties.
Equations
The deformation of horizontal wind is defined as 
, where 
and 
, representing the derivatives of wind component. Because these derivatives vary greatly with the rotation of the coordinate system, so do 
and 
.
Stretching direction
The deformation elements and (above) can be used to find the direction of the dilatation axis, the line along which the material elements stretch (also known as the stretching direction). Several flow patterns are characteristic of large deformation: confluence, diffluence, and shear flow. Confluence, also known as stretching, is the elongating of a fluid body along the flow (streamline convergence). Diffluence, also known as shearing, is the elongating of a fluid body normal to the flow (streamline divergence).
Plasticity (physics)
In physics and materials science, plasticity describes the deformation of a (solid) material undergoing non-reversible changes of shape in response to applied forces. For example, a solid piece of metal being bent or pounded into a new shape displays plasticity as permanent changes occur within the material itself. In engineering, the transition from elastic behavior to plastic behavior is called yield.
Plastic deformation is observed in most materials, particularly metals, soils, rocks, concrete, foams, bone and skin. However, the physical mechanisms that cause plastic deformation can vary widely. At a crystalline scale, plasticity in metals is usually a consequence of dislocations. Such defects are relatively rare in most crystalline materials, but are numerous in some and part of their crystal structure; in such cases, plastic crystallinity can result. In brittle materials such as rock, concrete and bone, plasticity is caused predominantly by slip at microcracks.
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