Adhesion-creepage characteristics of wheel/rail system under dry and contaminated rail surfaces.

摘要

This thesis presents an experimental and theoretical study of adhesion and creepage characteristics of wheel and rail under both dry and contaminated rail surfaces.;The experimental work was conducted largely on the IIT 1/4.5 Scale Wheel/Rail Simulation Facility. Based on the experimental data in the laboratory, a theoretical model of adhesion and creepage relationship with different degrees of contamination was developed.;Non-dimensional analysis of parameters yielded four important non-dimensional groups, which include the adhesion, creepage coefficients, the elastic properties of the materials, the load on the wheel surface roughness of wheel and rail, train speed and the contaminant density, viscosity and minimum film thickness.;Rail contaminants were gathered from several U.S. passenger rail systems and tested on the laboratory facility. It was found that presence of moisture reduce the adhesion levels with these contaminants. Under hot air jet applications, normal adhesion could be achieved.;A series of tests were conducted with water contamination on clean rail. Maximum adhesion for different tests was nearly constant and approximately 0.2. Maximum adhesion produced under water contamination is significantly affected by the average roughness of the wheel and the rail. As the roughness decreases, maximum adhesion drops sharply. Maximum adhesion also decreases with speed in the presence of moisture even at relatively low speeds (4--8 mph).;An empirical relation of maximum adhesion with axle load, speed and roughness has been derived.;An analytical expression for the adhesion-creepage curves under (TOR) lubrication has been derived. The maximum adhesion coefficient achieved for different (TOR) lubricant formulations was found to be approximately proportional to kinematic viscosity.;A theoretical approach for estimating potential energy savings with the (TOR) lubricant was developed using the laboratory data of the 1/12.5 scale simulator and 1/4.5 scale test facility simulator. It was found that the average energy savings by the lubricant were approximately 250 J/1muL. An attempt has been made to apply this result to full scale trains.