Date of Award

December 2016

Degree Type

Thesis

Degree Name

Master of Science

Department

Engineering

First Advisor

Anoop Dhingra

Committee Members

Benjamin Church, John Reisel

Keywords

Boundary Friction, Drag, Horizontal Terminal Motion, Mechanical Response

Abstract

In engineering and science literature, there seems to be a lack of consensus on a modeling framework clarifying how resistance to boundary motion affects mechanical performance. By mechanical performance, is implied the action of a force moving an object from one point to another that generates changes in position, velocity, acceleration and jerk. Apart from affecting a whole vehicle, critical power transmission components and subcomponents all rely on the mechanical responses that change due to an applied force. For example, the power needed to move an aircraft, an automobile, a ship, a submarine etc. will be reduced if resistance to their motion diminishes.

Of the three laws of friction, the first one stating friction as directly proportional to normal load is well known and almost universally proven. The second law asserting friction as independent of the area of contact has been found not to apply when rough surfaces are considered. Finally, the third law of friction proposing friction as independent of sliding velocity remains paradoxical considering that the dependence of friction on sliding velocity emerges demonstrably from the Stribeck effect and Stokes’ law of aerodynamic drag. To understand the dependence of friction on sliding velocity, this thesis establishes a deterministic framework for identifying boundary resistance effects on mechanical responses such as distance, velocity, acceleration, jerk, frequency, interacting forces, and efficiency. For this study, two cases are considered. The first case is considered to understand the effect of boundary friction and aerodynamic drag on mechanical sliding motion. In the second case, the effects of boundary friction on spring-resisted motion are explored. These two cases are further broken down into two sub cases, where the effects of constant and variable applied forces are separately investigated. The theoretical modeling effort shows that in general boundary resistance like solid friction and aerodynamic drag detrimentally impacts mechanical responses including efficiency during sliding. The deterministic framework created will be important for studying, synthesizing and designing future sustainable energy-efficiency technologies while dramatically improving existing technologies.

Available for download on Wednesday, February 27, 2019

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