TY - THES

T1 - Parametrization of a numerical model for rolling contact calculations

AU - Otipka, Dominik

N1 - no embargo

PY - 2024

Y1 - 2024

N2 - Cyclic contact between wheel and rail is a critical factor impacting the maintenance and service life of railway components. One key concern is ratcheting, a cyclic plastic deformation occurring under alternating loads. Additionally, changes in wheel and rail geometry influencing the contact surface further affect performance and durability, contributing to potential rail failures. To comprehensively investigate these relationships, Meyer developed a cyclic finite element model plugin [1]. The scope of this thesis is to extend the functionality of the existing plugin to provide a more detailed description of the plastic behavior of materials in cyclic rolling contact phenomena. Specifically, an investigation by using this extended plugin whether ratcheting or plastic shakedown occurs in materials subjected to multiple rolling cycles and various initial conditions takes place. To enable faster calculations, the wheel-rail geometry is simplified to cylindrical forms to create an elliptical contact patch based on Hertzian theory. A major optimization of the extended plugin includes evaluating only a specific selection of rollovers, thereby reducing simulation time. Furthermore, the model structure of the rail is simplified compared to the standard plugin by eliminating the need for sketch insertion, ensuring further optimization and easier creation of a parameter study. Thus, an extended plugin with automated creation of a wheel-rail model is developed, featuring an automated evaluation of contact parameters as well as stresses and strains in the rail. Using the optimized and extended plugin, a parameter study with different variants is conducted and carefully evaluated. The results of this parameter study are summarized in a comprehensive table that serves as a basic reference for future simulations with complex geometries and numerous real-world influences related to contact phenomena.

AB - Cyclic contact between wheel and rail is a critical factor impacting the maintenance and service life of railway components. One key concern is ratcheting, a cyclic plastic deformation occurring under alternating loads. Additionally, changes in wheel and rail geometry influencing the contact surface further affect performance and durability, contributing to potential rail failures. To comprehensively investigate these relationships, Meyer developed a cyclic finite element model plugin [1]. The scope of this thesis is to extend the functionality of the existing plugin to provide a more detailed description of the plastic behavior of materials in cyclic rolling contact phenomena. Specifically, an investigation by using this extended plugin whether ratcheting or plastic shakedown occurs in materials subjected to multiple rolling cycles and various initial conditions takes place. To enable faster calculations, the wheel-rail geometry is simplified to cylindrical forms to create an elliptical contact patch based on Hertzian theory. A major optimization of the extended plugin includes evaluating only a specific selection of rollovers, thereby reducing simulation time. Furthermore, the model structure of the rail is simplified compared to the standard plugin by eliminating the need for sketch insertion, ensuring further optimization and easier creation of a parameter study. Thus, an extended plugin with automated creation of a wheel-rail model is developed, featuring an automated evaluation of contact parameters as well as stresses and strains in the rail. Using the optimized and extended plugin, a parameter study with different variants is conducted and carefully evaluated. The results of this parameter study are summarized in a comprehensive table that serves as a basic reference for future simulations with complex geometries and numerous real-world influences related to contact phenomena.

KW - FEM Simulation

KW - Cyclic wheel-rail rolling contact

KW - Ratcheting

KW - Elastic-plastic material

KW - Rolling contact fatigue

KW - FEM Simulation

KW - Zyklischer Rad-Schiene Rollkontakt

KW - Ratcheting

KW - Elastisches-Plastisches Material

KW - Ermüdung durch Rollkontakt

M3 - Master's Thesis

ER -