Solid friction from stick–slip down to pinning and aging

By T. Baumberger, C. Caroli. 2005

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We review the present state of understanding of solid friction at low velocities and for systems with negligibly small wear effects. We first analyze in detail the behavior of friction at interfaces between macroscopic hard rough solids, whose main dynamical features are well described by the Rice–Ruina rate and state-dependent constitutive law. We show that it results from two combined effects: (i) the threshold rheology of nanometer-thick junctions jammed under confinement into a soft glassy structure and (ii) the geometric aging, i.e. slow growth of the real area of contact via asperity creep interrupted by sliding. Closer analysis leads to identifying a second aging-rejuvenation process, at work within the junctions themselves. We compare the effects of structural aging at such multicontact, very highly confined, interfaces with those met under different confinement levels, namely boundary lubricated contacts and extended adhesive interfaces involving soft materials (hydrogels, elastomers). This leads us to propose a classification of frictional junctions in terms of the relative importance of jamming and adsorption-induced metastability. Contents PAGE 1. Introduction 280 1.1. From Amontons--Coulomb to Rate-and-State 281 1.2. Spatial scales 284 1.3. Outline 285 2. Multicontact interfaces (MCIs) 286 2.1. Geometry of MCIs 286 2.1.1. Surface roughness 286 2.1.2. The single microcontact 287 2.1.3. Area of contact between random surfaces 289 2.2. Geometric age: a major state variable for MCIs 292 2.2.1. Time dependence of the static threshold 292 2.2.2. Creep growth of the real area of contact 294 2.2.3. Geometric age as a dynamical state variable 296 2.3. Junction rheology: gross features 298 2.3.1. Junctions at multicontact interfaces 298 2.3.2. A threshold rheology 299 2.3.3. Beyond threshold: rate effects 299 2.3.3.1. Velocity jumps: the direct effect 299 2.3.3.2. Steady sliding friction coefficient 301 2.3.4. Threshold rheology as a signature of multistability 303 2.3.4.1 A toy model for junction rheology 303 2.3.4.2. Monostable contact 304 2.3.4.3. Bistable contact 305 2.3.4.4. Rate effect at finite temperature 307 2.3.4.5. From the toy model to the real junction 308 2.4. Sliding dynamics of an MCIs 311 2.4.1. The Rice--Ruina friction law 311 2.4.2. The RR dynamics of a driven block 311 2.4.3. Limitations of block models for extended MCIs 315 3. Junction rheology: Structural aging/Rejuvenation effects 316 3.1. Accessing junction rheology directly: suitable configurations 317 3.1.1. Rough-on-flat multicontact interfaces 317 3.1.2. Junctions in the Surface Force Apparatus 318 3.1.3. Extended soft contacts 319 3.2. MCIs junctions revisited 319 3.2.1. Structural aging 320 3.2.2. Steady sliding dynamic friction 321 3.2.3. Discussion 321 3.3. Boundary lubrication junctions 322 3.3.1. Confinement-induced solidification 322 3.3.2. Structural aging 324 3.3.3. Sliding dynamics 324 3.4. Extended soft contacts: Gelatin/Glass friction 326 3.4.1. Static threshold 326 3.4.2. Sliding dynamics 327 3.4.3. Rate and state interpretation 329 3.5. Extended soft contacts: Dry elastomer friction 331 3.5.1. Bulk dissipation 331 3.5.2. Interfacial dissipation 331 3.6. A tentative classification: Jammed junction plasticity versus adsorption controlled dynamics 332 4. Conclusion 335 Acronyms 337 Acknowledgments 337 Appendix A: Shear stiffness of a MCIs 338 Appendix B: The viscoelastic GW model 339 Appendix C: The driven block: Linear stability analysis 341 Appendix D: The Schallamach model of adsorption-controlled friction 343 References 346

Subfields: Atomic and Molecular Physics, and Optics, Automotive Engineering, Mechanics of Materials

View Paper: https://www.semanticscholar.org/paper/da9a5ab12fe139c7de5bdb7a4ef06237595a66d9

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Citations in the corpus

Modeling and simulation in tribology across scales: An overview (2018, background): “Another cause for th e increase of is the strengthening of the contact with time, pre sumably due to relaxation of the glasslike material forming the very interface [462], or t the formation of chemical bonds [463], an effect denoted as structural aging [459].”
Does fault strengthening in laboratory rock friction experiments really depend primarily upon time and not slip? (2017, methodology): “…proxy (in units of time for the state evolution formulations we have chosen) for the strength of the asperities in contact across the sliding interface at a reference slip speed, often considered to scale with the true area of contact [Linker and Dieterich, 1992; Baumberger and Caroli, 2006].”