A fracture mechanical life prediction method for rolling contact fatigue based on the asperity point load mechanism

The purpose was to develop a fracture mechanics based method for determining the life of surface initiated rolling contact fatigue or spalling. The life simulations were based on the asperity point load mechanism, a mode I crack growth assumption and LEFM. The life prediction was verified against the spalling life in some gear teeth, which had been measured for the simulation data. The computational tool required an equivalent mixed-mode life parameter. Such are suggested in the literature and some of these were evaluated. Also, the work required material properties for crack growth at stress cycles with highly compressive minimum loads. An experimental series was performed for crack growth at R < 0. Negative crack closure limits KI,cl were suggested by the compliance but not the crack growth rate. Simulations with small negative closure limits KI,cl=-0.1MPam predicted the spalling life in the gears. It was however noted that the life predictions depended more on KI,cl than the equivalent mixed-mode life parameter.

► Life of surface initiated RCF in gears was predicted.
► Experimental investigation of some negative R-values on crack growth in gear steel.
► The asperity point load mechanism for surface initiated RCF was further validated.
► The influence of different closure limits was simulated.