# Strain

Strain, abbreviated as \(\epsilon\) (Greek symbol epsilon), a dimensionless number, also known as linear strain or longitudinal strain, is the deformation, stretched or compressed, of a material compared to its original length.

## strain Types

**Elastic Strain**- A transitory dimensional change that exists only while the initiating stress is applied and disappears immediately upon removal of the stress.

**Plastic Strain**- A dimensional change that does not go away when the initiating stress is removed.

## strain formula

\(\large{ \epsilon = \frac{ \Delta l }{ l_i } }\) |

\(\large{ \epsilon = \frac{ l_f \;-\; l_i }{ l_i } }\) |

### Where:

Units |
English |
Metric |

\(\large{ \epsilon }\) (Greek symbol epsilon) = strain | \(\large{\frac{in}{in}}\) | \(\large{\frac{mm}{mm}}\) |

\(\large{ \Delta l }\) = length change | \(\large{ ft }\) | \(\large{ m }\) |

\(\large{ l_f }\) = final length | \(\large{ ft }\) | \(\large{ m }\) |

\(\large{ l_i }\) = initial length | \(\large{ ft }\) | \(\large{ m }\) |

## Related formulas

\(\large{ \epsilon = \frac { \sigma } { \lambda } }\) | (elastic modulus) |

\(\large{ \epsilon = \frac { \sigma } { E } }\) | (Young's modulus) |

### Where:

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

\(\large{ \lambda }\) (Greek symbol lambda) = elastic modulus

\(\large{ \sigma }\) (Greek symbol sigma) = stress

\(\large{ E }\) = Young's modulus

Tags: Strain and Stress Equations Soil Equations Hoop Stress Equations