José A. Brandão

Surface damage prediction during an FZG gear micropitting test

A numerical simulation of an actual FZG spur gear micropitting test was performed. The simulation was based on a model that takes into account: overpressure effects due to mixed or boundary film lubrication, in turn caused by the interaction of roughness features of the contacting gear teeth, represented in the simulation by actual roughness profiles measured on the teeth; residual stresses in the gear teeth; a high-cycle, multi-axial fatigue criterion to evaluate the fatigue damage on the surface. The simulation was applied to the four load stages that constitute an FZG gear micropitting test and actual gear meshing was simulated. It was additionally possible to ascertain the adequacy of the model to shorter load durations because the load stages of the original micropitting test had been periodically interrupted for intermediate monitoring.

On the simulation of simultaneous fatigue and mild wear during a micropitting gear test

It has been observed that micropitting and wear are indissociable modes of surface damage of rolling element bearings. A similar observation was made concerning gears. This supports the idea that neither damage mechanism explains by itself the evolution of roughness during a micropitting test: they must be acting in concert. The present work investigates the integration of both damage mechanisms into a single numerical model of surface damage.

Gear Micropitting: Model And Validation

A numerical model for the prediction of surface initiated damage on gear tooth flanks (micropitting and mild wear) is presented. This model hinges on a model of the mixed film lubrication regime and on the application of the Dang Van highcycle multi-axial fatigue criterion. The numerical model developed was applied to the prediction of micropitting and mass loss of gear teeth in an actual micropitting test.