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Deformation of a straight rod / plate into a circle / tube.
Distortion of a square to a diamond-like 4-corner, for example through a shear force or shear load .
The object is moved from an undeformed starting position to a deformed position.

In continuum mechanics, deformation (also called deformation or distortion ) of a body is the change in its shape due to the action of an external force . The deformation can be used as change in length ( elongation ) or as an angular change ( shear ) appear. The deformation is represented using the strain tensor . The force of the body opposing the external force is the deformation resistance .


Deformations can be broken down into:

  • an isotropic part (isotropic change in size while maintaining the shape) and
  • a deviatoric part (change of shape while maintaining volume).

In addition, deformations consist of

Furthermore, deformations are divided into

  • spontaneous deformations and
  • viscous deformations.

Reversible elastic deformation

A reversible - i.e. a reversible or non-permanent - deformation is called elastic deformation . The associated material property is called elasticity .

Irreversible plastic deformation

Atomistic view of the plastic deformation under a spherical indenter in (111) copper. All atoms in the ideal lattice structure are omitted and the color code shows the von Mises stress field .

An irreversible, i.e. permanent, deformation once a flow limit has been reached is called plastic deformation . This requires that a material formability is; the associated property of a material is called plasticity .
The irreversible deformation of materials without a flow limit (e.g. most liquids) is called viscous deformation .

If the material is very brittle, it breaks without any relevant deformation beforehand. With rocks , this is the case with displacements in the millimeter to centimeter range per year, while slower processes take place plastically (see fold (geology) , tectonics ).

Primary plastic deformation can also be completely reversible on the nanoscale. This assumes that no material transport in the form of transverse sliding has yet started.

See also

Individual evidence

  1. ^ Gerolf Ziegenhain, Herbert M. Urbassek: Reversible Plasticity in fcc metals. In: Philosophical Magazine Letters. 89 (11): 717-723, 2009, doi : 10.1080 / 09500830903272900 .