Tuning friction with composite hierarchical surfaces

Abstract

Macroscopic friction coefficients observed in experiments are the result of various types of complex multiscale interactions between sliding surfaces. Therefore, there are several ways to modify them depending on the physical phenomena involved. Recently, it has been demonstrated that surface structure, e.g. artificial patterning, can be used to tune frictional properties. In this paper, we show how the global friction coefficients can also be manipulated using composite surfaces with varying roughness or stiffness values, i.e. by combining geometrical features with the modification of local friction coefficients or stiffnesses. We show that a remarkable reduction of static friction can be achieved by introducing hierarchical arrangements of varying local roughness values, or by introducing controlled material stiffness variations.Comment: 16 pages, 8 figure

A 2-D model for friction of complex anisotropic surfaces

“…The role of the weakest thresholds is confirmed also in [41], where it is shown that the distribution of the static friction thresholds deeply affect the global static friction and the onset of motion, while it is almost irrelevant for the dynamic phase. Thus, in a real material the nucleation points could be the contact points with imperfect contact on the surface.…”

“…One of the most widely used models is the one dimensional spring-block model, which was originally introduced to study earthquakes [29]- [31] and has also been used to investigate many aspects of dry friction of elastic materials [32]- [39]. In [40] we have extensively investigated the general behavior of the model and the effects of local patterning (regular and hierarchical) on the macroscopic friction coefficients, and in [41] we have extended the study to composite surfaces, i.e. surfaces with varying material stiffness and roughness; finally in [42] we have introduced the multiscale extension of the model to study the statistical effects of surface roughness across length scales.…”

Multi-Scale Surface Texturing in Tribology—Current Knowledge and Future Perspectives

“…Finally, Costagliola et al [234][235][236][237] proposed a spring-block modeling approach to investigate the fundamental mechanisms of dry friction between textured surfaces and how multi-scale surface textures influence static and dynamic friction. The model was used to show how the intricate surface geometry and local material properties on different length scales strongly affect the macroscopic friction force.…”

“…Finally, Costagliola et al [234][235][236][237] proposed a spring-block modeling approach to investigate the fundamental mechanisms of dry friction between textured surfaces and how multi-scale surface Figure 18. Overview of the multi-scale finite element method proposed by [233] to simulate hydrodynamic lubrication of large rough contact surfaces, which can be extended to deal with multi-scale textures.…”

Evidence of friction reduction in laterally graded materials

“…In this paper, we extend the previous work on 1D composite surfaces [ 30 ] to 2D geometries to show how it is possible to tune the macroscopic tribological properties through local variations of material and surface properties, i.e., Young’s moduli and friction coefficients, reducing static friction compared to the non-graded case. The results also allow the predictions of a discrete approach like the spring-block model [ 31 – 32 ] to be compared to those derived by explicit finite-element simulations.…”