PSI - Issue 7

Hisao Matsunaga et al. / Procedia Structural Integrity 7 (2017) 460–467 Hisao Matsunaga / Structural Integrity Procedia 00 (2017) 000–000

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4. Conclusions Rolling contact fatigue tests were carried out on JIS-6206 and JIS-51305 with small drilled holes of various diameters and depths. The results were evaluated using the Mode II stress intensity factor (SIF) range of ring-shaped cracks which emanated at the edges of the drilled holes. The conclusions can be summarized as follows: (1) The fatigue life data were uniformly gathered inside a narrow band, irrespective of the diameters and depths of the holes, by using the Mode II SIF range of ring-shaped cracks which originated around the edges of drilled holes. (2) In un-flaked specimens tested up to N = 1×10 8 cycles, short fatigue cracks were discovered at the edges. Such observations implied that the flaking limit of rolling bearings was not a crack initiation limit, but a non propagation limit of a fatigue crack. (3) It was determined that the crack-size dependency of the threshold SIF range, well-known for Mode I fatigue cracks, also exists in Mode II fatigue cracks, such as produced via rolling contact. The values of the threshold SIF ranges obtained from the RCF tests were in good agreement with those obtained in the torsional fatigue tests under static compression. After taking the crack-size dependency into consideration, the fatigue life data were uniformly evaluated. References Endo, M., Okazaki, S., Matsunaga, H., Moriyama, S., Munaoka, K., Yanase, K., 2015. A New Fatigue Testing Machine for Investigating the Behavior of Small Shear-Mode Fatigue Cracks. Experimental Techniques 40, 1065–1073. Cheng, W., Cheng, H.S., Keer, L.M., Ai, X., 1993. Surface Crack Initiation under Contact Fatigue: Experimental Observation and Contact Analysis. Transactions of the ASME, Journal of Tribology 115, 658–665. da Mota, V.M.M.B., Moreira, P.M.G.P., Ferreira, L.A.A., 2008. A Study on the Effects of Dented Surfaces on Rolling Contact Fatigue. International Journal of Fatigue 30, 1997–2008. Dommarco, R.C., Bastias, P.C., Hahn, G.T., Rubin, C.A., 2002. The Use of Artificial Defects in the 5-Ball-Rod Rolling Contact Fatigue Experiments. Wear 252, 430–437. Dommarco, R.C., Bastias, P.C., Rubin, C.A., Hahn, G.T., 2006. The Influence of Material build up Around Artificial Defects on Rolling Contact Fatigue Life and Failure Mechanism. Wear 260, 1317–1323. Fujii, Y., Maeda, K., 2002. Flaking Failure in Rolling Contact Fatigue Caused by Indentations on Mating Surface (I) Reproduction of Flaking Failure Accompanied by Cracks Extending Bi-Directionally Relative to the Load-Movement. Wear 252, 787–798. Furumura, K., Murakami, Y., Abe, T., 1993. The Development of Bearing Steels for Long Life Rolling Bearings Under Clean Lubrication and Contaminated Lubrication. Proceeding of 4th International Symposium on Bearing Steels, Creative Use of Bearing Steels, ASTM STP 1195, 199–210. Kida, K., Yamazaki, T., Shibata, M., Oguma, N., Harada, H., 2004. Crack Initiation from Micro Surface Holes in Bearings under Rolling Contact Fatigue. Fatigue & Fracture of Engineering Materials & Structures 27, 481–493. Kida, K., Yoshidome, K., Yamakawa, K., Harada, H., Oguma, N., 2006. Flaking Failures Originating from Microholes of Bearings under Rolling Contact Fatigue. Fatigue & Fracture of Engineering Materials & Structures 29, 1021–1030. Komata, H., Yamabe, J., Matsunaga, H., Fukushima, Y., Matsuoka, S., 2013. Effect of Size and Depth of Small Defect on the Rolling Contact Fatigue Strength of a Bearing Steel SUJ2. Transactions of the Japan Society of Mechanical Engineers A 79, 961–975. Matsunaga, H., Muramoto, S., Shomura, N., Endo, M., 2009. Shear Mode Growth and Threshold of Small Fatigue Cracks in SUJ2 Bearing Steel. Journal of the Society of Materials Science, Japan 58, 773–780. Matsunaga, H., Shomura, N., Muramoto, S., Endo, M., 2011. Shear Mode Threshold for a Small Fatigue Crack in a Bearing Steel. Fatigue & Fracture of Engineering Materials & Structures 34, 72–82. Murakami, Y., 1993. Application of Fracture Mechanics to Tribology Problems. Transactions of the Japan Society of Mechanical Engineers A 59, 283–290. Okazaki, S., Matsunaga, H., Ueda, T., Komata, H., Endo, M., 2014. A Practical Expression for Evaluating the Small Shear-Mode Fatigue Crack Threshold in Bearing Steel. Theoretical and Applied Fracture Mechanics 73, 161–169. Okazaki, S., Wada, K., Matsunaga, H., Endo, M., 2017. The Influence of Static Crack-Opening Stress on the Threshold Level for Shear-Mode Fatigue Crack Growth in Bearing Steels. Engineering Fracture Mechanics 174, 127–138. Otsuka, A., Sugawara, H., Shomura, M., Aoyama, M., Yoo, S.K., Shidata, M., 1994. Mechanism of Rolling Contact Fatigue and Mode II Fatigue Crack Growth–A Proposal on a Mode II Fatigue Crack Growth Test Method. Journal of the Society of Materials Science, Japan 43, 55–61.