Monofractal and multifractal behavior of worn surface in brass-steel tribosystem under mixed lubricated condition

The dynamic evolution law of brass surface in brass-steel tribopair during wear process is studied by using monofractal and multifractal methods. Wear tests are performed on a ring-on-disc tribometer under mixed lubrication. The profile of brass surface is measured by the reposition-measurement apparatus. Both the maximum peak-to-valley height Rt and the width of multifractal spectrum Δα decrease in running-in wear stage, maintain at a small value in steady wear stage, and increase rapidly in severe wear stage. While the evolution of fractal dimension is opposite to that of Rt and Δα. The results are instructive to wear state identification.