On an Elastoplastic Sliding Model for a Coated Single Asperity

Abstract

In this study, a sliding friction model for coated single asperity contacts is proposed. A displacement-driven layered contact algorithm is firstly introduced and verified by the finite element method. Then, this algorithm is applied to simulate the contact between two semispherical asperities. The full sliding contact process is discretized into a series of transient steps, and each of these steps are calculated by the displacement-driven contact algorithm. The effects of the interference depth and the properties of, respectively, the tribofilm (thickness, elastic modulus, and yield strength) and the nanocrystalline layer on the sliding coefficient of friction are investigated. The results suggest that when surface adhesion and asperity damage are ignored, the plastic deformation of the tribofilm is the main source of the sliding friction. Greater interference depth, tribofilm with greater thickness, higher elastic modulus or lower yield strength, and the presence of a nanocrystalline layer will lead to a higher coefficient of friction in single asperity sliding.

Relationship between Nano/Macrofriction Behaviors and Mechanical Properties of Tribofilms: An Investigation Using Multidimensional Nanoindentation Equipment

“…The number of measurement points was 36, and the mechanical properties were evaluated at 30 points, excluding the top and bottom of the measurement data. The Young's modulus was calculated for all samples assuming a Poisson's ratio ν of 0.3 [12,13].…”

A multi-technique characterization of the tribofilm formed by a fully formulated CVT fluid

“…where E is the Young's modulus of the tested sample, υ is the Poisson ratio of the tested sample, δ is the indentation depth, F adh is the adhesion force (pull-off force) and F n ¼ F DMT F adh . We assumed the υ to be 0.3 [51]. The F n , δ and F adh were calculated directly from the force-distance curves.…”

Sliding Interaction for Coated Asperity with Power-Law Hardening Elastic-Plastic Coatings

“…Dong et al [21] and Chen et al [22] developed a layered contact algorithm to study the contact between a rigid asperity and a coated elastic or elastic-plastic half space, which was solved by means of the Fast Fourier Transformation (FFT) technology. Recently, Wang and Schipper [23] used a similar method to study the sliding process of two elastic-plastic asperities with a nanocrystalline layer and tribofilms and to explore the effect of the mechanical properties of the tribofilm and the interference depth on the contact parameters. Most of these works considered the contact between a rigid asperity and an elastic or elastic–perfectly plastic half space.…”