Enhancement of elastohydrodynamic friction by elastic hysteresis in a periodic structure

Moyle, Nichole; Wu, Haibin; Khripin, Constantine Y.; Bremond, Florian; Hui, Chung‐Yuen; Jagota, Anand

doi:10.1039/c9sm02087j

Cited by 17 publications

(19 citation statements)

References 44 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results showed that, consistent with EHL theory, suitably normalized hydrodynamic friction plotted against the normalized sliding velocity collapses to a master curve, which means that elastohydrodynamic lubrication is controlled by a single dimensionless parameter (see below for definition), of which the inverse Hersey Number is an approximate version [13]. In our experiments, was found to be much larger than unity, which corresponds to the "Hertz" limit [18].…”

Section: Introductionsupporting

confidence: 84%

“…and (18). In SI (Section 5), we show that it is very well approximated by: Equations ( 19), ( 20) and (14) show that the maximum contact pressure, and friction force can be expressed in terms of minimum fluid layer thickness, the indentation depth and the compliance of the foundation; they are, for ≥ 10:…”

Section: Elastic Foundationmentioning

confidence: 85%

“…Our analysis is focused on the "Hertz" regime, in which the layer of liquid is thin and the elastic foundation deforms much as it would for dry frictionless indentation by the same indenter and load. The dominance of the Hertz regime is illustrated by our recent experiment [18,19]. Briefly, we slid a spherical glass indenter on the lubricated surface of an elastic polydimethylsiloxane (PDMS) substrate.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Friction Force During Lubricated Steady Sliding of a Rigid Cylinder on a Viscoelastic Substrate

Hui

Jagota

et al. 2021

Tribol Lett

Self Cite

View full text Add to dashboard Cite

We study the friction force during lubricated sliding of a rigid cylindrical indenter against a viscoelastic substrate in the iso-viscous visco-elasto-hydrodynamic lubrication (VEHL) regime. The substrate is represented by a foundation model. The solution is controlled by three dimensionless parameters. The first of these, λ, measures the time for the indenter to move one contact zone relative to the viscoelastic relaxation time; the second is the ratio of the long time to short time compliance of the substrate, c ∞ ∕c 0 ; the third parameter, β, is the ratio of average fluid flow rate to the sliding velocity. Although our solution works well for the full range of parameters, we focus on the "Hertz" regime (β >>1) where practically all the fluid in the contact region is squeezed out. This regime is quite common in soft contact lubrication problems and presents significant numerical difficulties. Our analysis gives insight into why these numerical difficulties arise. The friction force can be decomposed into two parts, one due to viscoelastic dissipation and the other from hydrodynamics. Although these two are generally coupled, in the Hertz limit, an important result is that the viscoelastic portion of the friction force can be well approximated by the solution of the corresponding "dry" sliding problem, in which there is no lubricating fluid layer. This provides a simple way to decouple the hydrodynamic portion of the friction force from the viscoelasticity of the substrate. We study how hydrodynamic pressure and film thickness vary with the controlling dimensionless parameters. Scaling laws for these relationships are given in closed form.

show abstract

Section: Introductionsupporting

confidence: 84%

Section: Elastic Foundationmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Friction Force During Lubricated Steady Sliding of a Rigid Cylinder on a Viscoelastic Substrate

Hui

Jagota

et al. 2021

Tribol Lett

Self Cite

View full text Add to dashboard Cite

show abstract

“…The previous EHD coupling is also widely encountered in soft condensed matter, but at very different pressure and velocity scales (Karan, Chakraborty & Chakraborty 2018). Examples encompass the remarkable frictional properties of eyelids (Jones et al 2008) and cartilaginous joints (Mow, Holmes & Lai 1984;Jahn, Seror & Klein 2016), as well as biomimetic gels (Gong 2006) and rubbers (Sekimoto & Leibler 1993;Moyle et al 2020;Wu et al 2020;Hui et al 2021). Of interest as well are the collisions and rebounds of spheres in viscous environments (Davis, Serayssol & Hinch 1986;Gondret, Lance & Petit 2002;Tan, Wang & Frechette 2019), the rheological properties of soft suspensions and pastes (Sekimoto & Leibler 1993;Meeker, Bonnecaze & Cloitre 2004), and the self-similar properties of the contact (Snoeijer, Eggers & Venner 2013).…”

Section: Introductionmentioning

confidence: 99%

Soft-lubrication interactions between a rigid sphere and an elastic wall

et al. 2021

View full text Add to dashboard Cite

The motion of an object within a viscous fluid and in the vicinity of a soft surface induces a hydrodynamic stress field that deforms the latter, thus modifying the boundary conditions of the flow. This results in elastohydrodynamic interactions experienced by the particle. Here, we derive a soft-lubrication model, in order to compute all the forces and torque applied on a rigid sphere that is free to translate and rotate near an elastic wall. We focus on the limit of small deformations of the surface with respect to the fluid-gap thickness, and perform a perturbation analysis in dimensionless compliance. The response is computed in the framework of linear elasticity, for planar elastic substrates in the limiting cases of thick and thin layers. The EHD forces are also obtained analytically using the Lorentz reciprocal theorem.

show abstract

“…As pressure-sensitivity of viscosity is negligible for typical soft lubrication conditions [34], we assume lubricant to be iso-viscous, i.e., Newtonian with constant viscosity. In our previous works [35,36], we have found that with appropriate normalization the EHL problem is governed by a single parameter which is a generalized version of the inverse Hersey number [11]. For soft contacts is typically much larger than 1.…”

Section: List Of Symbols Rmentioning

confidence: 99%

Lubricated Sliding of a Rigid Cylinder on a Viscoelastic Half Space

Jagota

Hui

2021

Tribol Lett

Self Cite

View full text Add to dashboard Cite

We study the lubricated sliding of a rigid cylinder on a viscoelastic half space with a single characteristic retardation time. Besides the generalized inverse Hersey number , which is the sole parameter governing elastic lubrication, the viscoelastic lubrication solution depends on two additional dimensionless parameters: and f . is the characteristic retardation time divided by the time for the rigid cylinder to move one contact width and f determines the strength of viscoelasticity. We have developed a numerical scheme to solve this viscoelastic lubrication problem. Our numerical results show that the total friction force can be decomposed into viscoelastic and hydrodynamic components. The viscoelastic component of the friction is well approximated by the dry limit in which the liquid layer is all squeezed out and the resistance to sliding is due entirely to viscoelastic dissipation. The hydrodynamic limit is well approximated by a modification of the elastic limit in which friction is due entirely to hydrodynamics. We also study the dependence of the hydrodynamic pressure, film thickness and the friction coefficient on these parameters.

show abstract

Enhancement of elastohydrodynamic friction by elastic hysteresis in a periodic structure

Abstract: Lubricated friction of soft contacts is enhanced by periodic variation of substrate compliance.

Cited by 17 publications

References 44 publications

Friction Force During Lubricated Steady Sliding of a Rigid Cylinder on a Viscoelastic Substrate

Friction Force During Lubricated Steady Sliding of a Rigid Cylinder on a Viscoelastic Substrate

Soft-lubrication interactions between a rigid sphere and an elastic wall

Lubricated Sliding of a Rigid Cylinder on a Viscoelastic Half Space

Contact Info

Product

Resources

About