In application lubricants are exposed to high rates of shear. As a result of their high content of additives of different kind, including high polymers, they can show a non-Newtonian rheological behaviour in hydrodynamic and elastohydrodynamic (EHD) lubrication. In viscometry with standard viscometers under low rates of shear, this anomalous flow behaviour does not appear. These lubricants can, therefore, become effective in bearing and gear application with another viscosity than is measured in viscometry. In addition to this, other flow effects can occur. The rheology of the lubricants certainly determines its behaviour in the hydrodynamic and elastohydrodynamic regimes. For this reason suitable rheological properties are a principle demand.
KeywordsShear Rate High Polymer Viscosity Index Hydrodynamic Lubrication Newtonian Theory
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