Modeling electrical resistance of lubricated contacts

In industry, it is not always possible to evaluate designs thoroughly and therefore modeling is an important tool in the design process. In this chapter, the basics of how to model a lubricated contact while also considering roughness and electrical contact resistance are discussed. When metal surfaces are brought into contact, the conduction between them is obstructed by gaps in contact. Roughness on the surfaces and nonconductive materials such as contaminants or lubricants cause these gaps. Models of this lubricated contact are complicated by the need to consider multiple scales of surface geometry in addition to electrical, solid, and fluid mechanics. If a lubricant film is present, relative motion between the solid surfaces can pressurize the film and separate the surfaces. In addition to reducing friction and wear from adhesion and abrasion, the film can increase contact resistance and, in some cases, induce electrical pitting of the surfaces. Therefore, the lubricant does not always have a positive effect. These multiphase and multiscale numerical models prove their worth by predicting the performance of the contacts. As will be shown, with the correct geometrical parameters, forces, velocities, and material properties, the models can predict film thickness, contact resistance, and friction, among other performance indicators.