Operating state-dependent modeling of the electrical impedance of cylindrical roller bearings for sensory utilization, taking into account mixed friction

• Applicant: Professor Dr.-Ing. Eckhard A. Kirchner
• Subject Area: Engineering Design, Machine Elements, Product Development
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556577310

The aim of the application is to understand the electrical impedance of rolling bearings with cage-guided cylindrical rollers and their sensory behavior over the entire operating range. A central component of this is the phenomenological description of the capacitance and resistance of the line contact without any correction factors. One focus is on the rolling element-to-board contact, the axial load-dependent influence of which on the impedance has not yet been investigated in detail. In addition, the influence of conductive cages, which has not yet been sufficiently described for deep groove ball bearings in the current state of research and can be investigated on the solid cage of a cylindrical roller bearing, will be examined. The proposed project thus closes important research gaps in the field of the electrical behavior of roller bearings, including mixed friction operation, which has hardly been investigated to date. Furthermore, the hypothesis that low measurement voltages have no influence on the service life and operating life of roller bearings will be tested. In order to achieve this goal, the following research questions (RQ) will be addressed in assigned work packages: RQ 1: How can the impedance of the cylindrical roller-raceway contact and the cylindrical roller-on-board contact be modeled phenomenologically when correction factors for operation in hydrodynamic lubrication are omitted? RQ 2: Which phenomenological models represent the electrical or sensory behavior of cylindrical roller bearings during operation in mixed friction with sufficient accuracy? RQ 3: How do conductive, roller-guided solid cages influence the electric field distribution and the resulting rolling bearing impedance, especially at low loads? RQ 4: Does the impedance measurement cause electrically induced structural changes? Analytical, but also semi-analytical and proven empirical equations are used in the theoretical modeling of the phenomenological relationships. In addition, the use of numerical simulations is expedient in order to consider and verify parts of the model in isolation. Varying the bearing sizes allows the geometric influences to be verified, while the change in load is aimed at the other impedance influences. The lubricant was not varied and the new reference lubricant (FVA project 852-II) was not investigated, as it is not comparable with the literature. The tilting and setting of the rollers is not investigated because these effects cannot be specifically adjusted on the test bench and models cannot be verified. A final verification of the models is planned as WP 5. At the end of the project, a verified calculation model will be available that calculates the impedance of single-row, combined loaded ball and cylindrical roller bearings. This will be made available to the public in the form of an open source repository.

• DFG Programme: Research Grants