NUST Institutions Library Catalogue

Advancements in engine design have necessitated use of synthetic, multi-grade engine
lubricants to reduce engine friction and wear and enhance its operational life. The modern multi-grade
oils exhibit the non-Newtonian characteristics which are beneficial for an effective lubrication of the
engines and industrial machinery. In the internal combustion engines, the piston ring assembly is a
crucial component of the power plant. In the four stroke cycle the 1st compression ring is an important
part of the piston ring pack which sustains the main combustion thrust directly. It is vulnerable to all
forms of dynamic loads during the extreme and unusual engine operating conditions. When an engine
starts up, the 1stcompression ring is most vulnerable to wear due to the absence of a fully established
Elastohydrodynamic Lubricating (EHL) film. In this context, the viscoelastic behavior of anon
Newtonian lubricant may contribute towards preventing wear of the interacting surfaces of the top ring
and the cylinder liner. Role of oil behavior to minimize adhesive wear of piston skirt and liner surfaces
during engine start up conditions under ideal conditions have yet to be properly modeled and
thoroughly investigated. This calls for proper investigative research to model rheological behavior of
non-Newtonian engine lubricants with particular focus on initial engine start up conditions.
This research work will numerically model the hydrodynamic and Elastohydrodynamic
Lubrication (EHL) of the 1st compression ring by considering the Newtonian and Non-Newtonian
lubricant characteristics for comparative analysis. The secondary dynamics of the piston will be
incorporated in the models at the different engine startup speeds, lubricant viscosities and radial
clearances for optimum solutions.