Description of the Lubricant Behavior Based on the Theory of Viscoelastoplasticity

The paper reviews the methodology of experimental and numerical study of greases. Anand model is taken for numerical description of its viscoelastoplastic behavior. The algorithm of material description is improved taking into account the dependence of model parameters on temperature (from -40 to +80 degrees Celsius). Two greases are considered: CIATIM-221; CIATIM-221F (superfine particles of polytetrafluoroethylene (PTFE) are introduced into the base) - manufacturer LLC "Center-Oil", Polevskoy city, Russia. The article found that the studied samples behave as a solid over the entire temperature range (from -40 to +80 degrees Celsius). The study of describing the lubricant as a Maxwell solid has been done previously. However, it was found that more sophisticated mathematical models are needed to qualitatively describe the behavior of grease over the entire range of operating conditions. The paper introduces an automated procedure for the numerical search for the optimal parameters of the extended Anand model for describing the thermophysical properties of greases. The procedure allows finding the model parameters in a wide range of temperatures (from -40 to +80 degrees Celsius) and obtaining the numerical distribution with an error of less than 5 %.