# Stress

Stress, abbreviated as \(\sigma \) (Greek symbol sigma), also called normal stress, is the force per unit area of cross-section. The maximum stress of a material before it breaks is called breaking stress or ultimate tensial stress.

## Stress Types

**Bulk Stress**(Volume Stress) - The volume of the body changes due to the stress.

**Compressive Stress**- The opposite of tensile stress.

**Cylinder Hoop Stress**- The circumference stress in a cylinder of pipe having both ends closed due to internal pressure.

**Fatigue Stress**- Failure or weakening of a material due to repetition and load cycling.

**Flow Stress**- When a mass of flowing fluid indicates a dynamic pressure on a conduit wall.

**Hoop Stress**- The circumferential and perpendicular stress to the axis imposed on a cylinder wall when exposed to an internal pressure load.

**Hydraulic Stress**- The internal force per unit area when the force is applied by the fluid on the body.

**Longitudinal Stress**- When the length of the body changes its length by normal stress that is applied.

**Pressure Stress**- Stresses induced in vessels containing pressurized materials.

**Radial Stress**- The stress towards or away from the central axis of a curved member.

**Residual Stress**- Stresses caused by manufacturing processes in a solid material after the origional cause has been removed.

**Shear Stress**(Tangential Stress) - Tends to deform the material by breaking rather than stretching without changing the volume by restraining the object.

**Structural Stress**- Stresses produced in structural members because of the weight they support.

**Tensile Stress**- A stress in which the two sections of material on either side of a stress plane tend to pull apart or elongate.

**Thermal Stress**- Whenever temperature gradients are present in a material.

## stress formula

\(\large{ \sigma = \frac{F}{A_c} }\) |

### Where:

Units |
English |
Metric |

\(\large{ \sigma }\) (Greek symbol sigma) = stress | \(\large{\frac{lbf}{in^2}}\) | \(\large{Pa}\) |

\(\large{ A_c }\) = area cross-section | \(\large{ ft^2}\) | \(\large{ m^2}\) |

\(\large{ F }\) = force | \(\large{ lbf }\) | \(\large{N}\) |

### Solve For:

\(\large{ A_c = \frac{ F }{ \sigma } }\) | |

\(\large{ F = \sigma \; a_c }\) |

## Related formulas

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

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

### Where:

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

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

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

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

Tags: Strain and Stress Equations Soil Equations Hoop Stress Equations Types of