Effect of Surface Roughness on Steel-Steel Dry Friction Coefficient

The influence of surface roughness magnitude and direction on dry static friction coefficient between two similar steel samples has been studied through an experiment. A testing apparatus has been designed and fabricated to measure the friction coefficient for a few forms of surface asperity. The average, maximum and minimum values of static friction coefficients among steel samples have been measured and numerically proposed in terms of some discrete values of the surface roughness, base and counter body angles. Correction coefficient defined as the ratio of maximum to minimum friction coefficient has been found on the result basis. According to the results of the experiments, dry static friction coefficient between two similar steel samples is affected by both magnitude and direction of surface roughness. Under the condition of static equilibrium, the Colomb - Amonton formula has been used to determine friction coefficient between samples. The flexibility and mass of the string have been neglected, and the reservoir pendulum-like swinging and the water movement therein have been avoided within the experiments.