Lubrication regimes in contact lens wear during a blink

In vitro friction testing of contact lenses and human ocular tissues: Effect of proteoglycan 4 (PRG4)

“…applied load and sliding velocity), and lubricants [20,[26][27][28][29][30][31][32][33]. In the presence of a contact lens, a numerical fluid model estimated that the eyelid exerts pressures of 12-18 kPa for sliding speeds of 10-100 mm/s [34]. The in vitro test setup used previously by Morrison et al [20] and Schmidt et al [19] is one method that has proved useful in assessing friction of contact lens biomaterials and ocular surfaces.…”

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

“…i) The fluid-asperity interactions occurring when the sliding direction is perpendicular to the grooves main direction (so called transverse roughness) is typically stronger than for the aligned grooves (longitudinal roughness), when the groove representative size is smaller than the smallest nominal contact length. This is well known in the literature of mixed lubrication for soft contacts [11,12] and of hydrodynamic lubrication for textured surfaces [13,14]. Thus, a larger asperity-induced fluid pressure is provided for the transverse roughness, which in turn determines an increased average interfacial separation (resulting from the decrease of the solid-solid contact pressure) and, therefore, a reduced dry contact area.…”

“…The Tripp number can be easily obtained from the 2D surface roughness power spectrum C(q x , q y ), see Ref. [17,11]. Thus, to determine the Tripp number accurately, topography measurements over surface areas rather than 1D line-scans are necessary.…”

“…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.…”

Elastohydrodynamics for Soft Solids with Surface Roughness: Transient Effects

“…In Sec. 3 we show theory results of the sliding kinematics for a sinus motion and a linear multi-ramp motion, and in particular we shed light on the squeeze-in and -out dynamics effects on the friction. In Sec.…”