Shaft Twist

Mechanical & Motion

Elastic angle of twist for a uniform circular shaft.

App id: MECH-11. Reference version 1.0.

How to fill it

Fill the inputs. The tool shows the outputs.

On the tool screen, Calc is the working sheet. Presets stores values you reuse. Reference is the formula, assumptions, and provenance below.

Formula

θ = T L / (J G)

Inputs

Name	Unit
Torque	`N-m`
Shaft length	`m`
Shaft diameter (optional)	`mm`
Polar moment J (optional)	`m4`
Shear modulus G	`GPa`

Outputs

Name	Unit
Twist (hero result)	`rad`
Twist	`deg`

Diagnose

Observations are context. They do not pass or fail a structure. See Diagnose.

When	Observation	Severity
`\|deg\| > 5`	Large elastic twist	caution

Assumptions

Uniform shaft, small deformation. Diameter computes solid-shaft J = πd⁴/32.
Shear modulus is a material input — steel is not assumed.

Provenance

Linear elastic torsion. Enter J directly or a solid-shaft diameter.