ABSTRACT
Rheology is the science and study of deformation and ¨ow of materials and, therefore, includes the study of linear elasticity of solids and Newtonian viscous ¨ow of liquids. However, in practice, rheology research tends to be interested exclusively in the constitutive equations which describe the complex behavior of non-Newtonian liquids. ˜e ¨ow conditions for tribological liquids are so severe that the temperature and pressure dependence of the viscosity is o§en of overwhelming importance relative to the non-Newtonian response. ˜erefore, it is proper to include temperature and pressure eµects in any discussion of rheology in lubrication. ˜e temperature dependence takes on even more importance when one considers that lubrication has a long history of mistaking viscous heating for non-Newtonian response [1].
