Project Details
Projekt
Auto-informative plain bearings – self-sufficient, temperature-based film thickness determination for condition monitoring in plain bearings
Subject Area
Engineering Design, Machine Elements, Product Development
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 466775494
The condition monitoring of machine elements is of fundamental importance for the dissemination of digitalization in mechanical engineering. With the aid of condition monitoring, critical operating states and incipient damage to machine elements can ideally be detected online without delay. By detecting damage at an early stage, machines can be serviced as needed, so that planned service intervals can be extended, and costs saved. The most important variables for identifying life-limiting conditions in plain bearings are the lubrication film thickness and the bearing temperature. Commonly used monitoring systems - such as cost-intensive, cable-based inductive displacement sensors - are usually retrofitted to plain bearings. Furthermore, implementation in multi-axis rotating systems, such as planetary gears, requires a considerable effort. Therefore, the aim of this research project is to develop and validate a method for a temperature-based, self-sufficient, wireless film thickness condition monitoring system for hydrodynamic plain bearings. The measuring system should be able to be integrated directly in the plain bearing and should enable reliable condition monitoring without influencing the primary function, even in the mixed friction area. The principle solution to be used for the auto-informative plain bearing is the Seebeck effect. This allows for a simultaneous temperature measurement and a self-sufficient energy supply using low-cost components. In addition to the storage and transmission of the variables bearing temperature and film thickness, a warning signal is to be triggered either when specified limit temperatures are exceeded or when a critical film thickness is reached. The critical film thickness limit represents the transition towards mixed friction. In fluid friction, the limit temperature is determined by the permissible operating temperature of the material, oil and sensor system. The temperature limit in mixed friction represents an experimentally determined scuffing temperature limit. The theoretical basis of temperature-based film thickness monitoring is the relationship between the shaft displacement angle and the film thickness. Using so-called Guembel curves, the minimum film thickness can be determined directly from the shaft displacement angle. To determine the shaft displacement angle, the position of the resulting temperature field in the load zone is used in the planned project. To derive the displacement angle from the temperature field, a TEHD model is used for calculating the film thickness and will be coupled with an FE model for calculating heat conduction. By considering different operating points, a characteristic diagram is determined, which is integrated in the measurement system and allows the determination of the film thickness from the measured temperature field in-situ. Finally, a model for transfer to other sizes based on the Guembel curve is developed and experimentally validated.
DFG Programme
Priority Programmes
Subproject of
SPP 2305:
Sensor-Integrated Machine Elements pave the way for Widespread Digitalization
Co-Investigator
Dr.-Ing. Francisco Gutiérrez Guzmán
