# Deformation

Written by Jerry Ratzlaff on . Posted in Classical Mechanics Deformation, abbreviated as $$\delta$$  (Greek symbol delta), is measured by how much an object is deformed from its origional dimensions.

## Deformation Formulas

$$\large{ \delta = \frac{ F\;l_i }{ A_c\;\lambda } }$$
Symbol English Metric
$$\large{ \delta }$$  (Greek symbol delta) = deformation $$in$$ $$mm$$
$$\large{ A_c }$$ = area cross-section $$in^2$$ $$mm^2$$
$$\large{ \lambda }$$  (Greek symbol lambda) = elastic modulus $$\large{\frac{lbf}{in^2}}$$ $$\large{Pa}$$
$$\large{ F }$$ = force $$\large{lbf}$$ $$\large{N}$$
$$\large{ l_i }$$ = initial length $$\large{ft}$$ $$\large{m}$$

## 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. 