Hydrodynamic plain bearings are widely used in heavy-duty applications, e.g., wind turbine drivetrains or ship propulsion systems. However, abnormal events such as mechanical overload causing overheating or particle contamination can lead to rapid bearing damage and the failure of the entire drivetrain. Most existing condition monitoring systems (CMS) cannot detect particle contamination and mechanical overloading in a timely manner or are associated with high costs and installation effort that limit their practical applicability. In this paper, temperature field measurement (TFM) is investigated as a promising approach to address this gap via the development of a sensor-integrating plain bearing (SiPB) prototype. The approach is characterized by its low cost and low energy demand, with the potential for autarkic operation through the thermoelectric harvesting of the frictional waste heat within the bearing. In both overheating tests, characteristic signal discontinuities in the temperature field occurred at least 10 min before the friction torque limit was reached, which served as the criterion for terminating the experiment. Particle contamination resulted in a pronounced increase in the scattering in the temperature field over the entire duration of the experiment compared to regular operation. The interquartile range ($IQR$) of the mean temperature was identified as a promising characteristic; in the single-contamination test, the $IQR$ was increased by a factor of 2.6 compared with regular operation. These characteristics were derived descriptively from one test per abnormal event; repeated tests are required to validate them. The energy demand of the SiPB prototype is determined as a function of the sampling rate (1.3 mW at a sampling rate of 0.2 Hz). The temperature differences required for cold start and the supply mode of the DC-DC converter necessary for supplying the required operating voltage of the SiPB prototype via thermoelectric energy harvesting are determined (approximately 2 and 5 K, respectively). Based on simulation data, this corresponds to the magnitude of temperature differences expected in the plain bearing during normal operation, meaning that the autarkic operation of the SiPB can be enabled in the future.

Hydrodynamic plain bearings are characterized by their high load-carrying capacity, good damping properties and resistance to short-term abrasive wear. Therefore, plain bearings are widely used in heavy-duty applications, e.g., wind turbine drivetrains or ship propulsion systems . However, certain abnormal operating conditions can lead to rapid bearing damage. This may result in failure of the entire drivetrain. Two such abnormal events are mechanical overload causing overheating of the bearing and damage caused by particle contamination. Condition monitoring systems (CMS) exist for hydrodynamic plain bearings and numerous measurement methods currently represent the state of the art. However, most of these systems cannot detect particle contamination and mechanical overloading in a timely manner or are associated with high costs and installation effort that limit their practical applicability. Consequently, there is a need for a CMS approach that enables the timely detection of particle contamination and mechanical overloading. In this paper, temperature field measurement (TFM) is presented as a suitable approach to address this gap. The developed approach is characterized by its low cost and low energy demand. The energy efficiency of the developed Sensor-integrating Plain Bearing (SiPB) allows the CMS to operate autarkically by utilizing the waste heat generated by friction during regular operation within the plain bearing. Timely detection of the aforementioned failure causes requires a correspondingly high sampling rate, which in turn results in relatively high energy consumption. Therefore, the energy requirements of the SiPB prototype are discussed in relation to the measurement strategy and the resulting need to optimize both energy consumption and operating strategy is addressed. Subsequently, the temperature differences required to meet energy demand and ensure autarkic operation of the SiPB are determined. Finally, a measurement strategy for the autarkic operation of the SiPB is defined.