Hamrock-Dowson Film Thickness
Minimum EHL film thickness in elliptical point contact (rolling-element bearings): h_min / R = 3.63 · U^0.68 · G^0.49 · W^(-0.073) · (1 − e^(-0.68k)).
h_min / R
0.00001862 -
Formula, assumptions, and limits
U = η·u / (E'·R), G = α·E', W = w / (E'·R²). For marine bearings lambda = h_min/σ_composite. λ > 3 full hydrodynamic; 1 < λ < 3 mixed lubrication; λ < 1 boundary - high wear rate.
Symbol legend
| Symbol | Meaning | Unit | Source |
|---|---|---|---|
| Speed parameter | - | velocity, viscosity | |
| Material parameter | - | pressure-viscosity coeff | |
| Load parameter | - | contact load | |
| Contact ellipticity | - | geometry |