A multi-physics, multi-scale numerical simulation technique is presented for modeling gearboxes operating under loss-of-lubrication conditions. Accordingly, the tool includes components for contact mechanics, tribology associated with EHL through boundary lubrication regimes, CFD modeling of the gearbox flow, conduction within the gears, housing and other gearbox components, and free convection to the external environment. These component physics models are coupled in a fashion that accommodates their disparate space and time-scales. This paper describes each sub-model in detail, and the space-time coupling strategies used. Results are presented for a spur-gear test stand operated at NASA Glenn Research Center. The physics of the eventual runaway temperature excursions subsequent to loss-of-lubrication are captured. Model shortcomings and attendant future work are identified.
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