Deformation (mechanics)

As distortion or deformation of a body is referred to in the continuum mechanics, the change of its shape due to the action of an external force. The deformation can occur as a change in length or angle change in appearance. The external force opposing force is the resistance to deformation of the body.

Deformations are divided into:

• Plastic deformation or irreversible deformation
• Elastic deformation or reversible deformation
• And the mixed form partly plastic (only partially reversible ), eg in deflections.

Irreversible plastic deformation

An irreversible, so durable, deformation is called plastic deformation. The corresponding property of a material is called plasticity or ductility. A prerequisite is that a material can be deformed, ie has a low brittleness.

At very high brittleness breaks the material without deforming relevant previously. In rocks, this is already at bends in the millimeter to centimeter range per year the event, while slower processes plastic drain (see fold ( geology), tectonics ).

At the nano- scale the primary plastic deformation can be completely reversible. This assumes that no material transport has been used in the form of cross slip.

Reversible elastic deformation

A reversible - that is an irreversible or permanent - deformation is called elastic deformation, however. The corresponding material property is called elasticity.