Access Type

Open Access Dissertation

Date of Award

January 2012

Degree Type


Degree Name



Mechanical Engineering

First Advisor

Nabil G. Chalhoub


Frictional losses in internal combustion engines approximately account for 10% of the expended fuel energy. Moreover, forty percent of these losses are attributed to the reciprocating motion of the piston-assembly. Besides the adverse effect of friction on fuel economy, the intricate dynamics of the piston-assembly tend to significantly influence the thermal efficiency through blow-by, the engine durability through wear, and the engine noise through piston-slap. Moreover, 40 to 80% of the lubricant oil consumption has been attributed to the ring-pack dynamics.

In this dissertation, a reliable tool has been developed using MATLAB/SIMULINK and embedded C-S Functions that predicts the intricate dynamics and lubrication regimes of the piston-assembly under various engine operating conditions. The current formulation considers the interconnected motions of the crankshaft, the connecting-rod, the piston (both primary and secondary motions), and the ring-pack using a multi-body dynamic approach. Curved beam Finite Element method for Timoshenko beams was used to account for the longitudinal and in-plane transverse deformations of the rings. Furthermore, the interaction between piston skirt, ring running surface, and the lubricating oil film was included in order to predict hydrodynamic and elasto-hydrodynamic lubrication regimes.