Ultimate Rheology Comparer
Compare lubricants under real operating conditions: viscosity and density of up to three lubricants as functions of temperature, pressure and shear rate, from measured database data.
What the app does
Datasheets give viscosity at 40 °C and 100 °C and atmospheric pressure. Real contacts run hotter or colder, at pressures up to the GPa range and at shear rates of millions per second. The Ultimate Rheology Comparer predicts the viscosity and density of up to three lubricants at the operating point you choose, using rheological models fitted to lubricant data held in the i-TRIBOMAT tribology database.
Models
- Walther — temperature dependence only, at 0.1 MPa (the basis of the ASTM D341 viscosity–temperature chart).
- Roelands — adds the pressure dependence of viscosity.
- Roelands + Carreau–Yasuda — adds shear thinning at high shear rates.
Each lubricant can use a different model. Where a model is not valid for the chosen conditions, the table shows N/A and the curve is hidden, so you never read an extrapolation as data.
Inputs and outputs
- Operating point: temperature (15–120 °C), pressure (0.1–1000 MPa) and shear rate (10 to 10⁷ 1/s).
- Results table: kinematic viscosity ν, density ρ and dynamic viscosity η for each lubricant at that point.
- Plots of kinematic viscosity, density and dynamic viscosity against temperature, and relative viscosity against shear rate.
Typical uses
- Choosing between candidate oils for a bearing, gear or test.
- Getting realistic viscosity inputs for film-thickness and friction calculations — for example in the EHL Film Thickness Simulator.
- Comparing a new formulation with a reference lubricant.
Want your lubricants in the comparison? Contact us at office@i-tribomat.eu — we characterise viscosity, density and high-pressure rheology in our partner laboratories.
How to access the app
The Ultimate Rheology Comparer runs in your web browser on Tribology Universe, the app platform of i-TRIBOMAT: The European Tribology Centre. Use is free; you only need a Tribology Universe account, which takes a minute to create.
Need more than the free app?
Our Modelling & Simulation team builds custom models for your geometry, materials and lubricants, and can validate them against tests on more than 130 tribometers across our partner laboratories. Contact us or write to office@i-tribomat.eu.
References
- C. J. A. Roelands, Correlational aspects of the viscosity–temperature–pressure relationship of lubricating oils, PhD thesis, TU Delft, 1966
- C. J. Seeton, Viscosity–temperature correlation for liquids, Tribology Letters 22 (2006) 67–78
- S. S. Bair, High Pressure Rheology for Quantitative Elastohydrodynamics, 2nd ed., Elsevier, 2019
- H. Spikes, Z. Jie, History, origins and prediction of elastohydrodynamic friction, Tribology Letters 56 (2014) 1–25
- Viscosity calculator: Barus and Roelands equations, TriboNet