Theory of lubrication of elastomeric rotary shaft seals

Abstract

Current knowledge of the principles of rotary lip seal operation is assessed through a review of the experimental foundation and the key theoretical models. Studies of the existence of the lubricating film, the load support mechanism, the sealing mechanism, the thermal effects and the followability are described.

Theory of viscoelastic lubrication

“…Due to the (approximately) steady-state contact condition occurring at the roughness length scale, the flow as well as the frictional correction factors, entering in Eqs. (2) and (4), are similar to those developed in Ref. [23] for the elastic solid bulk rheology, with the only difference that in this case the rubber elastic modulus, which enters in the correction factors calculation through the Persson 0 s contact mechanics [19], is varying with the sliding velocity (see later).…”

“…Fluid viscosity η ¼ 10 À 4 Pa s. from being Grubin 0 s like. 2 Due to the very different nature of the rubber and the fluid bulk rheologies, the rubber rolling friction as a function of velocity has a maximum related to the maximum of the loss tangent, whereas the fluid-pressure asymmetry, and its contribution to the friction, increases continuously with increasing sliding velocity.…”

“…It involves contact mechanics between rough surfaces, and polymer dynamics of compliant bodies, and it occurs in a remarkably wide range of applications such as tire-road contact [1], rubber sealing [2,3] and wiper blades contacts [4], in the mechanics of biological interfaces [5,6] and, consequently, of bio-inspired (e.g. adhesives [7]) and bio-medical devices (e.g.…”

Elastohydrodynamic Analysis of a Rotary Lip Seal Using Flow Factors

“…Similarly, the first term on the right-hand side of Eq. [2] represents the flow in the y direction due to the pressure gradients in the x and y directions, and the remaining term represents the flow in the y direction due to the motion of the shaft. φ xx, φ xy , φ yy , and φ yx are the pressure flow factors, φ s,c,x and φ s,c,y are the shear flow factors, and φ c,c is the density flow factor.…”

Influence of anisotropic surface roughness on lubricated rubber friction: Extended theory and an application to hydraulic seals

“…Soft contacts are crucial in numerous engineering and biological applications, and have gained increasing attention by scientists working in fundamental science [1][2][3] and computational mechanics [4]. Soft contacts occur, e.g., in the tribology of machine elements [5][6][7][8][9][10], in living matter [11][12][13], and medical devices [14,15], to name just a few. In some specific applications, the wet grip performance becomes the subject of international regulation, such as for tires (e.g.…”