Abstract
The premature flaking called white structure flaking (WSF) or white etching crack (WEC) often occurs in rolling bearings used for automotive electrical components, wind turbine gearboxes, etc. This phenomenon is understood to be intimately associated with shear mode (Mode II and III) fatigue crack growth caused by cyclic shear stress in the presence of large compressive force. In some studies, it is reported that hydrogen which is generated by decomposition of lubricant spread into a rolling bearing and affects the service life of rolling bearings for long-term use. In order to ensure the safety and integrity of rolling bearing, the effect of hydrogen on the shear mode fatigue crack growth and threshold behavior needs to be fully understood. Mode I fatigue crack growth is accelerated by hydrogen and this hydrogen effect becomes significant with decrease in test frequency. This phenomenon implies that the similar frequency effect would occur also in shear mode fatigue. To the best of author’s knowledge, however, there are no studies that investigated the effect of hydrogen and frequency on the shear mode fatigue crack in high-cycle fatigue. The objective of this study is to investigate the effect of hydrogen and frequency on the shear mode fatigue crack growth and threshold behavior by a multiaxial fatigue testing machine combined with a continuous hydrogen-charging system.