# Deformation

Written by Jerry Ratzlaff on . Posted in Classical Mechanics

Deformation is measured by how much an object is deformed from its origional dimensions.

### Deformation formula

$$\large{ \epsilon = \frac{ \delta }{ l_i } }$$

Where:

$$\large{ \epsilon }$$  (Greek symbol epsilon) = strain

$$\large{ \delta }$$  (Greek symbol delta) = deformation

$$\large{ l_i }$$ = initial length

### Elastic deformation

Elastic deformation is when strain is applied and disappears immediately when the stress is removed.

### Plastic deformation

Plastic deformation is when strain is applied and does not disappear when the strain is removed.  When the load on a material has passed its elastic limits or yield stress the deformation becomes perminent.

### Deformation wear

Deformation wear is a result of repeated plastic deformation at the wearing surface, producing a surrounding structure of cracks that grow and combine to form wear particles.