elastohydrodynamiska

Elastohydrodynamic lubrication (EHL) is a specialized branch of fluid mechanics that studies the behavior of thin films of lubricant under high pressure and relative motion, typically found in tribological systems such as rolling-element bearings, gears, and contact surfaces in machinery. Unlike traditional hydrodynamic lubrication, which assumes rigid surfaces, EHL accounts for the deformation of both the lubricant film and the solid surfaces, leading to more accurate predictions of film thickness, friction, and wear.

The phenomenon arises when two asperities (roughness features) on opposing surfaces come into contact under load, compressing the lubricant film between them. Under these conditions, the lubricant experiences significant pressure, often exceeding 100 MPa, which can cause it to deform elastically or even plastically. The combined effects of pressure, temperature, and surface elasticity result in a non-Newtonian fluid behavior, where viscosity varies with shear rate and pressure. This interaction is crucial for maintaining effective lubrication, as it helps distribute loads and reduce friction and wear.

Mathematical modeling of EHL involves solving coupled partial differential equations that describe fluid flow, heat transfer, and elastic deformation. Key parameters include the Hertzian contact pressure, lubricant viscosity (which may be pressure-dependent), surface roughness, and material properties of the contacting solids. Numerical methods, such as finite element analysis, are commonly used to simulate EHL conditions due to the complexity of the governing equations.

Applications of EHL research include optimizing lubrication in automotive and aerospace components, improving the efficiency and longevity of industrial machinery, and developing advanced lubricants with tailored properties. Understanding EHL is essential for reducing friction losses, minimizing wear, and enhancing the reliability of high-performance tribological systems.