Leakage mechanism in flat seals

Abstract

We present a theoretical approach to estimate the fluid leakage in flat seals. The approach is based on the analogy between the seal-substrate interface and a porous medium. We assume that the interface is constituted of a random distribution of noncontact patches (the pores) and small but numerous contact spots (islands). Leakage may occur only through the pores, of which the lateral size and height are distributed according to a probability density function that we calculate on the basis of a recent theory of contact mechanics. Our theoretical approach is based on a percolation scheme that has never been proposed before and we believe it could be useful to stimulate further theoretical or experimental investigations. Within this percolation scheme we apply critical path analysis to calculate the hydraulic conductivity of the medium and compare our predictions with other calculations very recently presented to the scientific community.

A theoretical and experimental study of viscoelastic rolling contacts incorporating thermal effects

“…Indeed, the two shapes match quite well, confirming the utility of the proposed BE method for a variety of problems, e.g. from seals to tyres technology [2] [3] . In all these cases, changes in the contact area obtained by varying the relative speed are of particular importance.…”

“…Furthermore, viscoelasticity entails a strong dependence of contact area, penetration and, therefore, contact stiffness on the speed of motion. This, for example, may have a paramount importance in seals where fluid percolation is closely related to the real contact area( [2] [3]). Finally, due to the marked dependence of the viscoelastic properties on the material temperature, the thermal heating caused by sliding or rolling motion should be quantified in order to to optimize the components design [12].…”

“…Currenly, much attention is paid to soft matter mechanics and, in particular, to improve our understanding of problems involving surface interactions. Soft material mechanics is, in fact, crucial for a number of engineering applications including tyres and seals ( [2] [3]) , bioengineering [4], nanotechnology [5] and "green" technology [6]. The behaviour of these components is complicated by viscoelastic contact mechanics.…”

Percolation Properties of the Free Volume Generated by Two Rough Surfaces in Contact

“…Similarly, the features of the leakage domain by considering the statistical proprieties of the surface height distribution were investigated in the literature. As highlighted by Dapp [7], the role of the finite size length and the lower cut-off frequency of the rough surface mainly affect the topology of the free volume and, consequently, leakage characteristics [1]. All of those studies pinpoint the fact that, below the full contact limit, morphological proprieties of the surface affect percolation of a fluid between two rough surfaces.…”

“…The mechanism of percolation in seals or simply between two rough surfaces in contact is an interesting topic for physics and engineering [1,2,3]. This topic is relevant for many applications such as hydraulic fracturing and sealing of mechanical components in contact.…”