Contact Analysis of a Nanocomposite Surface with Two Particle Size Distributions for Magnetic Particulate Tapes

Abstract

The coating layer of magnetic particulate tapes consists of magnetic and nonmagnetic particles of different sizes on a polymeric matrix, which makes the tape surface have a bimodal or trimodal roughness distribution. In this study, an algorithm is developed to generate composite surfaces with two size distributions of particles. The composite surface is generated by superimposing large and small particles with radii following a Gaussian distribution on a random Gaussian surface, with the centers of the large particles sitting on the mean plane of a rough surface and the centers of the small particles sitting on the superimposed surface of large particles and a rough surface. Statistical analysis is carried out for the generated composite surfaces to study the effects of the particle distribution on the surface's probability density functions (PDFs) and roughness parameters. Also, contact analysis is conducted to identify particle distribution for low friction and wear. Variation of the fractional contact area, the maximum contact pressure, and the relative meniscus force with four design variables as well as the mean radius ratio, the standard deviation ratio, and two particle densities are studied. It is found that a higher mean radius ratio and standard deviation ratio and lower particle densities give a lower contact area, which is desirable for low friction; for low wear, the converse is true. It is recommended that a composite surface with a higher mean radius ratio is most desirable for low friction. On the other hand, for low wear, a lower mean radius ratio is recommended.