A Mixed Hydrodynamic Lubrication Model for Armature-Rail Interface Considering Surface Contact Characteristics

The operational environment characterized by ultrahigh-speed friction in electromagnetic launching causes the armature with a low melting point to melt. A portion of the liquid film is transferred onto the guideway, thereby elevating the interface roughness. This phenomenon leads to the destabilization of the liquid phase, rendering it incapable of fulfilling the necessary lubrication functions. Therefore, it is necessary to analyze the mechanism of interface roughness on the state of the liquid film. This study integrates electromagnetic-stress-fluid multiphysical field coupling conditions and develops a mixed hydrodynamic lubrication model that incorporates the dynamic pressure effect, roughness characteristics, and elastic deformation. The research investigates the impact of varying roughness magnitude and asperity surface patterns on the interfacial pressure, liquid film thickness, load-bearing capacity, and friction coefficient of the armature rail (A/R) contact. Furthermore, the mixed lubrication contact mechanism at the A/R interface is analyzed. The results show that the transverse interface texture and minimal roughness can enhance the thickness distribution and pressure-bearing capacity of the metal liquid film. This effect reduces the probability of direct interface contact, mitigates the transition phenomenon resulting from interfacial liquid film rupture, and consequently extends the operational lifespan of the electromagnetic launch rail.