One commonly used lubricant in rolling bearings is grease, which consists of base oil, thickener and small amounts of additives. Commercial greases are mostly produced from petrochemical base oil and thickener. Recently, the development of base oils from renewable resources have been significantly focused on in the lubricant industry. However, to produce an entirely bio-based grease, the thickener must also be produced from renewable materials. Therefore, this work presents the design and evaluation of three different bio-based polymer thickener systems. Tribological tests are performed to characterize lubrication properties of developed bio-based greases. The effect of thickener type on film thickness and friction behavior of the produced bio-based greases is evaluated on a ball-on-disc tribometer. Moreover, the results are compared to a commercial petrochemical grease chosen as benchmark.

Model-based systems engineering (MBSE) is an auspicious approach to the virtual development of cyber-physical systems. The behavior of the system’s elements is thus represented by specialized simulation models that are integrated into the descriptive SysML-based system model. Although many simulation models have been developed in research for the common system elements for various purposes and fidelities, their integration remains a major challenge: the parameter interfaces of the simulation models must be coupled with each other and with the parameters of the system elements in such a way that they are correctly parameterized. So far, this coupling can only be carried out by model experts in a time-consuming and error-prone manner. Therefore, in this paper, we first propose a concept that structures the system element parameters for targeted use in validation and design cases. Second, we propose a model signature for simulation models that differentiates its parameters by input, internal, output, and model parameters and specifies them with spatial and temporal dimensions as well as admissible ranges, among others. Based on the two contributions, domain models can be validly and automatable coupled and used for the virtual development of system elements in model-based systems engineering.

Nowadays, more than 90% of all rolling element bearings are grease lubricated. Grease releases oil to separate the contacting surfaces by forming a stable oil film, thus resulting a long service life of a bearing. The film thickness is usually calculated by assuming fully flooded conditions. However, if the amount of released oil is insufficient, the film thickness will be reduced, which is termed as starvation. Grease lubricated rolling bearings have the risk of starvation even at fairly moderate speeds, which implies a high risk of wear and bearing failure. To reduce this risk, an accurate starvation model to predict film thickness under starvation is needed. In this contribution, a new starvation model based on the CFD method is used. The effects of starvation on film thickness and surface deformation are analyzed. For starved condition, film thickness at contact sides still remains fully flooded but decreases around contact center line because of the spring-back resilience of the material. Meanwhile, with increasing speed, the maximum deformation increases.