# Torsion Constant for Ellipse Cross-section

## Torsion Constant for Ellipse Cross-section formula

\(\large{ J = \frac{\pi\;a^3\;b^3}{a^2\;+\;b^2} }\) |

### Where:

Units |
English |
Metric |

\(\large{ J }\) (Greek symbol alpha) = torsion constant | \(\large{\frac{lbf-ft}{rad}}\) | \(\large{\frac{N-m}{rad}}\) |

\(\large{ a }\) = semi-major axis of an ellipse | \(\large{in}\) | \(\large{m}\) |

\(\large{ b }\) = semi-minor axis of an ellipse | \(\large{in}\) | \(\large{m}\) |

\(\large{ \pi }\) = Pi | \(\large{3.141 592 653 ...}\) |

Tags: Strain and Stress Equations Constant Equations Torsion Constant Equations