Drive shaft fatigue strength in bending

Maximum static and cyclic bending moment for a drive shaft at a critical, notched cross-section, from tensile strength and stress concentration factor.

✓ validated against legacyoriginal: /calculators/f_2.htm

Drive shaft fatigue strength in bending — original diagram from /calculators/f_2.htm

Shaft diameter, d_k10⁻³ mTensile strength, Rp0.2MPaDynamic/static tensile strength ratio, σₑ/Rp0.2Stress concentration factor, Kₜ or K_f

Section modulus for bending, S = I/(d_k/2) = (π/32)d_k³0.79 10⁻⁶ m³

Maximum bending moment, statically loaded, Mb = S·Rp0.2392.7 Nm

Maximum bending moment, cyclically loaded, Mb = S·σₑ/Kₜ80.32 Nm

Method & references

Fatigue strength of a drive shaft in bending, at a notched/grooved cross-section.

The computation is a literal port of the original client-side JavaScript from /calculators/f_2.htm. Results are verified equal to the original by an automated golden-master test. No formula has been re-derived or “improved”.

Drive shaft fatigue strength in bending — Engineering ABC