Date of Award

Fall 2014

Degree Type


Degree Name

Master of Science (MS)


Mechanical Engineering

First Advisor

Monika Ivantysynova

Committee Member 1

Andrea Vacca

Committee Member 2

Farshid Sadeghi


Axial piston machines are widely used in current industries such as aerospace, agriculture, automotive, heavy machinery, military, etc. Thus new cost-effective and highly efficient designs with better performance and reliability are needed. These new, high efficient pumps and motors will also aid in new applications such as hybrid hydrostatic transmissions and displacement controlled actuation. The aim of this work is to study how to reduce the energy dissipation (increase efficiency) while also improving the load carrying ability of the fluid film between the piston and the cylinder through surface shaping of the piston over a wide range of operating conditions. The impacts of this study also include the utilization of modern manufacturing technologies as low tolerances are necessary such that this could affect the overall efficiency of the machine drastically. This study could also open up ways to use water as a lubricating fluid in order to significantly reduce costs. In doing so, a comprehensive understanding of the phenomena occurring between the piston and cylinder will also be achieved in order to find a balance between the viscous friction of the fluid, while reducing any contact occurring, and the leakage. In order to verify the code used in this surface shaping study, a comprehensive study was conducted on the baseline and then compared to measurements.