Influence of stress conditions in roller bearings on the damage mechanism of White Etching cracks (WEC)

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The research objective of the project is the investigation of the mechanical, thermal and chemical stress conditions which create white etching cracks (WEC). Systematic variations of parameters in experiments are used to identify the individual influence of parameters for growing of crack meshes. With the knowledge of these important parameters it is possible to work out the mode of action in the damage process and derive remedial actions to avoid these bearings failures. Beside the reproduction of white etching crack damages it is also intended to identify a condition monitoring procedure to identify damages at an early stage and to investigate the influence of the bearing size.Three research sites in Kaiserslautern and Hannover (Institute of Machine Elements, Gears, and Transmissions (MEGT), University of Kaiserslautern, Working Group of Materials Testing (AWP), University of Kaiserslautern, Institute for Mechanical Components, Engineering Design and Tribology (IMKT), Leibniz University of Hannover) provide their expertise and their laboratory equipment. Component tests are performed at the MEGT under triaxial dynamic loads using existing electric and hydraulic drives. In addition multi-body simulation is used to investigate the internal bearing dynamics and especially the associated contact forces and stresses. The IMKT develops a system model based on component-related test specimen. This model describes the internal stresses of the bearing rings. Moreover the rolling element track contact is studied in detail using a specialized tribometer. The AWP is focused on single- and multi-axial stressing of test specimen. The experience and equipment of the AWP is also used to investigate samples of the other institutions to identify WEC. Results of an institute are directly forwarded to the other institutions for verification, for example regarding a load scenario with WEC formation.