Torsional Constant Calculator

Your details

Outer radius of the solid circular shaft.
mm
Twisting moment applied to the shaft. Leave at 0 to skip twist calculations.
N-mm
Length of the shaft over which the torque is applied.
mm
Shear modulus of the material. Steel: ~80,000 MPa (11,600,000 psi). Aluminium: ~26,000 MPa (3,800,000 psi).
MPa
Torsional constant J
613,592.315mm⁴

St. Venant torsion constant for the selected cross-section.

Angle of twist0.0006degrees
Max shear stress0.04MPa
Angle of twist (rad)0.00001rad
Torsional constant J613,592.315
Max shear stress0.04

J = 613592.315 (length⁴) for the selected solid circle

  • The solid circle has a torsional constant of 613592.315 length⁴, which determines how stiff the section is against twisting.
  • The angle of twist (0.0006 deg) is very small, indicating a stiff shaft for this loading.
  • Maximum shear stress is approximately 0.04 stress-units. Compare this against the material yield strength divided by a factor of safety (commonly 1.5 to 2.5).
  • The solid circle gives the highest J for a given enclosed area, making it the most torsion-efficient solid section.

Next stepCross-check the shear stress against your material allowable, and review the twist angle against any deflection limits in the design code.

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