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Eintrag

Kategorie:
Prüfsysteme

Art des Gerätes:
Rolling contact fatigue test rigs / Wälzfestigkeitsprüfstände

Bezeichnung der übergeordneten Forschungsinfrastruktur (optional):
Institut für Werkstoffanwendungen im Maschinenbau

Zusätzliche Methoden und Synergien mit anderen Geräten (optional):
Surface and subsurface damage can be characterized.

Identifikationsnummer (optional):
iwm-19

Kurze Beschreibung des Gerätes (maximal 5000 Zeichen):
The developed test rig is designed for the experimental investigation of damage mechanisms in rolling bearings under defined and reproducible operating conditions. A particular focus is placed on the analysis of White Etching Areas (WEA) and White Etching Cracks (WEC), which are characterized by branched, three-dimensional crack networks beneath the component surface as well as locally altered, nanocrystalline microstructures. These damage phenomena often occur unexpectedly and are still not fully understood. In addition to these specific failure modes, the test rig also enables general investigations of rolling contact fatigue, making it a versatile tool for tribological and material-related studies. The test rig is hydraulically operated and allows for the precise application of defined mechanical loads. The specimen features a cylindrical raceway and is mounted on a central drive shaft. Loading is applied via a hydraulically actuated pivoting arm, ensuring controlled and continuous force transmission. The radial load is introduced through three rollers arranged at 120° intervals, resulting in identical normal loading conditions in all three rolling contacts. This configuration ensures uniform stress distribution on the specimen and enables efficient testing through simultaneous loading of multiple contact zones. During operation, the specimen experiences three load cycles per revolution of the motor, leading to accelerated fatigue loading. The rotational speed of the drive system can be varied between 600 and 3,000 rpm. The Hertzian contact pressure can be adjusted within a range of 1,000 to 3,500 MPa, allowing the simulation of both moderate and highly loaded operating conditions. A vibration sensor mounted on the pivoting arm is used to monitor the system condition and can serve as a potential shutdown criterion in the event of damage initiation. A key feature of the test rig is the targeted variation of tribological and physical influencing parameters. Lubrication conditions can be adjusted by using different lubricants and by varying the specific lubricant film thickness. The oil inlet temperature can be controlled within a range of 50 to 95 °C, enabling the investigation of thermal effects. Additionally, four discrete slip conditions are available (SRR: 0%, -8%, -17%, and -26%), which are implemented using interchangeable gearbox modules. This allows for the controlled study of different relative motions within the rolling contact. The influence of hydrogen on material behavior can be investigated indirectly by testing specimens that have been pre-charged with hydrogen prior to installation in the test rig. This approach enables the assessment of hydrogen-related effects on crack initiation, crack propagation, and microstructural alterations without requiring an active hydrogen charging system during operation. By combining mechanical, tribological, and thermal influencing factors, the test rig enables the systematic study of complex interactions. Individual parameters can be varied independently in order to isolate their specific effects on the formation of WEA/WEC as well as on general rolling contact fatigue behavior. The high reproducibility of the experimental conditions represents a key requirement for obtaining reliable and comparable results. Overall, the test rig represents a tool for the investigation of damage mechanisms in rolling bearings. In addition to the targeted analysis of specific failure modes such as White Etching Areas and White Etching Cracks, it is particularly suitable for fundamental studies on fatigue strength, lifetime prediction, and the evaluation of the influence of different operating and environmental conditions on material behavior.

Hersteller:
custom-built test rig / Eigenbau

Jahr des Erwerbs (optional):
1998

Modell:
Four-disc test rig / Vier-Scheiben-Prüfstand

Notwendige / einschränkende Rahmenbedingungen für den Einsatz (optional):
Suitable specimen geometry; Hertzian contact pressures: 1,000 - 3,500 MPa; Four discrete slip ratios: 0%, -8%, -17%, -26%; Oil inlet temperatures: 50 - 95 °C; Electrical current densities: 0.1 - 4.3 A/mm²; Motor speed: 600 - 3,000 rpm

Nutzergruppen:
Internals and externals

Art der Nutzung:
Service (intern and extern)

Fakultät:

• Faculty 4 – Mechanical Engineering

Fachgruppe / Lehreinheit (optional):
Mikromechanik

Institutskennziffer (IKZ):
418110

Website (optional)
https://www.iwm.rwth-aachen.de/cms/IWM/Forschung/Arbeitsgebiete/Werkstoffmechanik/~hewpp/Mikromechanik/?lidx=1

Adresse (optional):
Turmstraße 46, 52064 Aachen

Ansprechpartner*in:
Alexander Bezold

E-Mailadresse (optional):
services@iwm.rwth-aachen.de