Neu, Marcel (2022)
On the Numerics of Electrical Phenomena in Thermo-Elasto-Hydrodynamic Rolling Contacts.
Technische Universität Darmstadt
doi: 10.26083/tuprints-00021647
Dissertation, Erstveröffentlichung, Verlagsversion

Kurzbeschreibung (Abstract)

This work presents the methodological development of a simulation toolbox intended for the Fluid-Structure Interaction calculations of rolling bearings contacts, combined with electrostatic fields. A numerical analysis of the Thermal Elastohydrodynamic Lubrication in electrically burdened rolling bearing contacts becomes possible through the presented implementations. The differential equations, models, and coupling mechanisms necessary for such calculations are extracted from the literature in this work’s fundamentals. Based on the Fluid-Structure Interaction extension of foamExtend 4.0, a program architecture is created to represent the theoretical framework. Each new implementation is verified and validated against established numerical or analytical tests following the Test-Driven Development practice. Since no reference calculation or experimental data for electrical phenomena in isolated Thermal Elastohydrodynamic Lubrication contacts is available at the point of submission, a data set suited for the final validation is acquired experimentally. The experimental setup used for the data acquisition and the processed data itself is also part of this work. A two-dimensional numerical case for reference calculations is introduced to compare the experimental results. Necessary discretization- and solution procedures are chosen based on common standards for numerical computations. However, a validation of the calculation procedure against the experimental data failed due to problems that arose by transferring the Fluid-Structure Interaction calculation to the Elastohydrodynamic Lubrication scale. The radial bearing loads used during the experiments are, as of now, not calculable with the proposed numerical setup. Reasons for this are discussed, and solutions are proposed. Although the final validation has not yet been carried out, the code was used in the performant parameter limits to interpret experimental studies. The insights gained into the electrical behaviour of imperfect surfaces and the influence of ionisation on damage mechanisms is a scientific added value. The insights gained from these calculations are discussed against the background of possible new fields of application for the toolbox since electric phenomena are now within the scope of numerical Thermal Elastohydrodynamic Lubrication calculations. Since those Thermal Elastohydrodynamic Lubrication calculations are the basis for damage analysis in rolling bearings the extension allows for the research of electric damaging mechanisms as well. Causes for the limitations are evaluated, and improvements to overcome the prevailing problems are stated. This work concludes with a discussion of research areas that are recognized as promising. The assessment of those areas is based on this work’s insights and the author’s gathered experience.

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