Twin Disc Testing as a Method of Evaluation of Rolling Contact Fatigue in Camring Steel
Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
The aim of the present work was the investigation of the use of the twin disc machine testing as an experimental method to simulate, identify and evaluate rolling contact fatigue in a short time for different combinations (ESR and standard) of cam ring steels with different case heat treatments (tempered at 180˚C and 240˚C). The ring samples were machined to achieve an elliptic contact in order to increase the contact pressure and achieve fast results. The contact pressure was calculated according to the Hertzian formula taking in account the shape parameters of the rings. The tests were performed with higher or lower amount of cycles depending on the previous results (cracks found or not) and for different contact pressures. The contact area was SEM inspected after each test. Friction and wear plots were used as fatigue criteria complementarily to the SEM analysis. The tests conditions (shape, roughness, friction coefficient) were studied and appeared to cause a scatter in the results because of their variation from one sample to another affecting the stress distribution, type of damage and the lubrication regime (film thickness). Therefore, the stress distribution was simulated under the elliptic contact surface taking in account, these parameters (shape parameters, roughness, friction coefficient). The tests showed that the twin disk testing method was useful for pitting detection in RCF under lubrication. Meanwhile, the quality of the samples was of extreme importance in order to keep constant conditions in different runs. The contact area SEM inspection after each test showed that high contact pressures induce adhesive damage in the samples that may accelerate RCF damage. The highest rolling contact fatigue limit was observed for the ESR steels.
Place, publisher, year, edition, pages
2011. , 51 p.
Technology, Rolling contact fatigue (RCF), twin disk tests, electro slag remelted (ESR) steel, heat treatment, stress distribution, friction coefficient, roughness value, hertzian elliptic contact pressure
IdentifiersURN: urn:nbn:se:ltu:diva-53849Local ID: ad8bedc6-92f9-4119-aba9-bbebbeb54335OAI: oai:DiVA.org:ltu-53849DiVA: diva2:1027226
Subject / course
Student thesis, at least 30 credits
Materials Engineering, master's level
Validerat; 20110921 (anonymous)2016-10-042016-10-04Bibliographically approved