Under CopyrightSchmitz, KevinFaust, MatthiasSufiyan, AbuAbuSufiyan2025-11-182025-11-182025https://publica.fraunhofer.de/handle/publica/499494https://doi.org/10.24406/publica-646310.24406/publica-6463In this study, a dedicated test rig was equipped with vibration, acoustic, and thermographic sensors to investigate the effects of grease degradation on bearing behaviour. Custom 3D-printed sensor mounts were designed to ensure reproducible positioning, enabling consistent data acquisition across multiple runs. Three lubrication conditions - Good, Medium, and Bad - were created by thermally aging the same base grease for different durations in a climate cabinet, thereby simulating progressive degradation stages. Measurements were then performed under controlled operating conditions, and the acquired data were processed and analyzed using Python-based tools. The evaluation revealed that thermography showed the strongest potential for distinguishing between lubrication states. After offset and reference correction, the Good-Medium pair displayed a clear and stable thermal deviation compared to the reference, whereas the Good-Bad state remained inconsistent and changed its behaviour after approximately twenty minutes in both experiments. The thermal deviation curves reached steady plateaus after warm-up, with the largest deviations observed for the Medium state and smaller for the Bad state. Vibration and acoustic analyses, on the other hand, exhibited less distinct trends. While the outer accelerometer occasionally indicated slightly higher energy in the 1-3 kHz range for the degraded greases, these effects were small and not reproducible across all runs. The harmonic-band averages around the shaft’s rotational frequency and its first harmonics showed some variation between lubrication states but lacked overall consistency. Similarly, the microphone data revealed weak low-frequency tendencies after background subtraction, with higher-frequency components remaining close to the noise floor. It can therefore be concluded that, under the present test conditions, thermography provided somewhat reliable differentiation between lubrication states and demonstrated sensitivity to thermal effects caused by grease degradation, but without achieving the same runtime with Good-Bad as of Good-Medium, nothing concrete can be said. The vibro-acoustic data, although capturing certain spectral tendencies, did not yield a clear separation and may require more advanced signal analysis or extended measurement durations to fully exploit their diagnostic potential.enThermal CameraDegredationVibrationVibro-acousticAccelerometer600 Technik, Medizin, angewandte Wissenschaftenbachelor thesis