Shaft Fatigue

Estimate a torsional Goodman fatigue safety factor for a shaft.

Live concept view — geometry scales with the entered design condition.

Estimate a torsional Goodman fatigue safety factor for a shaft.

PRELIMINARY RESULT

Torsional fatigue safety factor2.40

Formula: 1/n = τa / Se + τm / Su

A linear Goodman-style torsional fatigue relation combines alternating and mean shear stress.

FORMULA VERIFICATION

Reference: Shigley, Mechanical Engineering Design, circular-shaft torsion and elementary beam theory.

Internal unit basis: N, mm, MPa and SI rotational units converted explicitly. Outputs: tool-specific SI engineering units.

Valid conditions: Positive finite geometry, load and source-controlled property inputs.

Limitations: Preliminary elastic screening only; no code-compliance, detailed stress concentration or service spectrum design.

Design inputs