Driveshaft Critical Speed
Euler-Bernoulli first-mode critical RPM with safety-factor recommendation.
Example
You enter
- OD (in) 3.5
- Wall (in) 0.083
- Length between U-joints (in) 48
- Material steel
You get
- Critical RPM 9823
- Recommended max (0.65x) 6385 rpm
Details, formula, and sources
Euler-Bernoulli first-mode whirl (simply-supported, eigenvalue (βL)² = π²): N_crit (RPM) = (π² / L²) × sqrt((E × I) / (ρ × A)). Recommended max operating = 0.65 × N_crit (engineering-practice safety margin).
Euler-Bernoulli beam theory by name; AAM (American Axle) and Spicer / Dana driveshaft engineering manuals by name.
Beam-theory principles free in mechanics-of-materials texts at university OCW.
Estimate. AHJ and licensed professional govern.
Field names used by the API: od_in, wall_in, length_in, material, critical_rpm, recommended_max_rpm
- Material moduli / densities from data/construction or user-supplied; steel E = 30e6 psi / ρ = 0.283 lb/in³ defaultengineering reference
- Operating margin 0.65 × N_crit recommendedAAM / Spicer engineering manuals