転がりすべり疲労におけるき裂発生・進展挙動の連続観察 : 潤滑油の粘度と汚染度の影響

The objective of the research reported in this paper is to study fatigue crack initiation and propagation behavior under cyclic rolling-sliding contact using a notched cylindrical specimen. Since flaking and preflaking cracks were limited in notched area where contact pressure was high, the surface appearance in notched area could be observed continuously by the replica method. While surface cracks were not found until 97% of the flaking life in the case where clean oil with high viscousity was used, surface crack initiations at surface flaws of indentations were observed on specimens tested with dirty of low-viscous oil. It was also found that the crack propagation rates were almost constant when the crack length was greater than 0.3mm and that crack propagation rates in specimens lubricated with dirty oil are the same as of smaller than those with clean oil.