Friction dependence on surface patterns

• Main Author: Lim, Xinglin.
• Other Authors: Fan Hui
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering::Mechanical engineering
• Online Access: http://hdl.handle.net/10356/53977
• Institution: Nanyang Technological University

As study of friction is an important aspect in most engineering and industrial applications, this report would cover a further study in said area. Experimentation was carried out on various substrates with varying surfaces: smooth, isotropic and anisotropic. Each substrate surface will present a different surface roughness, hence a comparison will be done between the three surfaces to analyse the effect of the surface roughness of the surfaces in relation to the static friction. The effect of the direction of the wavelengths of the isotropic and anisotropic substrate surfaces were also studied in this project. The production of anisotropic surfaces differ from that of the isotropic substrate surfaces by that of a process that requires the substrate to be strained under a temperature above its glass transition temperature. The differences of the coefficients of static friction are compared in the later part of the report. From the results of the experiment, it was found that the coefficient of static friction calculated for isotropic surfaces are smaller than those calculated for smooth surfaces. This is explained using a theoretical model by Rand et. al., where the adhesion energy between surfaces were lower for isotropic surfaces, or surfaces with higher surface roughness, than those between smooth surfaces. It was also observed that as the surface roughness increased, the coefficient of static friction measured decreased. For anisotropic surfaces, it was found that the coefficient of static friction calculated for the sliding in the direction parallel to the wrinkle wavelength was higher than that in the direction perpendicular to the wrinkle wavelength. The process of local fracture at the sliding edge was attributed to this observation. It was also observed that the values of the coefficient of static friction followed the trend observed in the isotropic substrate experiments.