# Torsion constant (Circle -cross-sectional shape)

## Description

In solid mechanics, torsion is the twisting of an object due to an applied torque. The torsion constant is a geometrical property of a bar’s cross-section which is involved in the relationship between angle of twist and applied torque along the axis of the bar, for a homogeneous linear-elastic bar. The torsion constant, together with material properties and length, describes a bar’s torsional stiffness. It is identical to the second moment of area for concentric circular tubes or round solid shafts.

Related formulas## Variables

J_τ | Torsion constant (m^{4}) |

π | pi |

D | The diameter of the circle (m) |