Transient flash-temperature prediction using asperity microcontact pressure for rough-textured gear-tooth surfaces under mixed lubrication

Localized frictional heating at rough gear interfaces is strongly influenced by transient heat generation at discrete asperity contacts, whereas conventional flash-temperature methods represent the contact using an equivalent macroscopic heat source. This study develops an asperity-resolved transient heat-transfer framework for rough-textured gear contacts under mixed lubrication. A cavitation-aware rough-textured thermal plasto-elastohydrodynamic lubrication (R-TPEHL) model is coupled with an elastoplastic asperity-contact model to determine local film thickness, fluid-solid load sharing, real contact pressure, and temperature-dependent deformation. The resolved asperity pressure is converted into discrete moving frictional heat sources, and the transient temperature field is obtained using a Green's-function solution with interfacial heat exchange. The original rough surface and four textured counterparts are evaluated at three load levels and multiple positions along the line of action. Increasing load reduces film separation and intensifies asperity heating, raising the maximum flash temperature of the original surface from 83.46 to 260.92 °C. Texture performance depends on load, morphology, and meshing position: all textures reduce the peak temperature under light load, whereas edge-induced pressure concentration weakens this benefit at medium and heavy loads. Relative sliding velocity governs the global temperature trend, while load sharing, local film state, and microcontact migration determine local peaks. Across the three sequential CFD–FEM benchmark cases, the differences in peak pressure and flash temperature are 2.0–3.2% and 5.5–12.6%, respectively. The framework supports local thermal-risk identification and load- and position-dependent texture design.