deformation

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 .

separations

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).

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.