Scale effects in friction using strain gradient plasticity and dislocation-assisted sliding (microslip)

Scale effects in dry friction at macro- to nanoscale are considered. According to the adhesional model of friction, the friction force depends on the real area of contact and the average shear strength of asperity contacts during sliding. The scale dependence of the so-called geometrically necessary dislocations causes enhanced hardness with decreasing scale. In the case of plastic contacts, enhanced hardness results in a decrease in the real area of contact. The average shear strength at the interface is associated with dislocation-assisted sliding (microslip) and increases with decreasing scale, from geometrical considerations. In cases of single-asperity and multi-asperity elastic or plastic contact, the scale dependence of the real area of contact and shear strength results in scale-dependent friction. Comparisons of the model with experimental data are also presented.

[1]  Robert W. Carpick,et al.  Measurement of interfacial shear (friction) with an ultrahigh vacuum atomic force microscope , 1996 .

[2]  B. Bhushan.  Contact mechanics of rough surfaces in tribology: multiple asperity contact , 1998 .

[3]  Huajian Gao,et al.  Mechanism-based strain gradient plasticity— I. Theory , 1999 .

[4]  J. Weertman.  Dislocations moving uniformly on the interface between isotropic media of different elastic properties , 1963 .

[5]  J. Greenwood,et al.  Contact of nominally flat surfaces , 1966, Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences.

[6]  B. Bhushan.  Contact Mechanics of Rough Surfaces in Tribology: Single Asperity Contact , 1996 .

[7]  K. Johnson,et al.  Adhesion and friction between a smooth elastic spherical asperity and a plane surface , 1997, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[8]  B. Bhushan,et al.  Introduction to Tribology , 2002 .

[9]  Juan A. Hurtado,et al.  Scale effects in friction of single–asperity contacts. I. From concurrent slip to single–dislocation–assisted slip , 1999, Proceedings of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[10]  M. Ashby,et al.  Strain gradient plasticity: Theory and experiment , 1994 .

[11]  Udo D. Schwarz,et al.  Quantitative analysis of the frictional properties of solid materials at low loads. I. Carbon compounds , 1997 .

[12]  Bharat Bhushan,et al.  Thin-film friction and adhesion studies using atomic force microscopy , 2000 .

[13]  Bharat Bhushan,et al.  Micro/nanoscale friction and wear mechanisms of thin films using atomic force and friction force microscopy , 1998 .

[14]  Huajian Gao,et al.  Indentation size effects in crystalline materials: A law for strain gradient plasticity , 1998 .

[15]  Bharat Bhushan,et al.  Effect of normal load on microscale friction measurements , 1996 .

[16]  B. Bhushan,et al.  Atomic-Scale Friction Measurements Using Friction Force Microscopy. Part 1. General Principles and New Measurement Techniques , 1994 .

[17]  Vikram Deshpande,et al.  Discrete dislocation plasticity modeling of short cracks in single crystals , 2003 .

[18]  B. Bhushan,et al.  Nanoindentation and picoindentation measurements using a capacitive transducer system in atomic force microscopy , 1996 .

[19]  Huajian Gao,et al.  Mechanism-based strain gradient plasticity—II. Analysis , 2000 .

[20]  U. Landman,et al.  Nanotribology: friction, wear and lubrication at the atomic scale , 1995, Nature.

[21]  J. Hutchinson.  Plasticity at the micron scale , 2000 .

[22]  Patricia McGuiggan,et al.  Fundamental experimental studies in tribology : the transition from interfacial friction of undamaged molecularly smooth surfaces to normal friction with wear , 1990 .

[23]  Leon M. Keer,et al.  Scale Effects of Elastic-Plastic Behavior of Microscopic Asperity Contacts , 1995 .

[24]  B. Bhushan,et al.  Contact mechanics of multilayered rough surfaces , 2002 .

[25]  B. Bhushan,et al.  Fractal Model of Elastic-Plastic Contact Between Rough Surfaces , 1991 .

[26]  J. Archard,et al.  The contact of surfaces having a random structure , 1973 .

[27]  Bharat Bhushan,et al.  Nanoscale tribophysics and tribomechanics , 1999 .

[28]  Zdeněk P. Bažant,et al.  Scaling of dislocation-based strain-gradient plasticity , 2002 .

[29]  B. Bhushan,et al.  Development of AFM-based techniques to measure mechanical properties of nanoscale structures , 2002 .