Correlation between Spatial Fractal and Temporal Chaos During the Sling Wear Process of AISI 5120 Steel

The purpose of this paper is to investigate the relationship between surface morphology and friction coefficient during the wear process. Different wear stage tests of AISI 52100 ring sliding against AISI 5120 disc were designed and performed. The fractal and chaos theories were employed to study the spatial and temporal features of surface structure and friction signal, respectively. It is found that the disc worn surface has a 3D fractal nature, and the friction coefficient signal has a chaotic nature. Additionally, the correlation coefficients between the fractal dimension D and standard deviation of distance matrix STD, and multifractal spectrum width [Formula: see text] and STD, were −0.7727 and 0.7130, respectively. The absolute values of both correlation coefficients greater than 0.5 indicate a strong similarity between spatial fractal and temporal chaos in the friction system. This characteristic is beneficial to online recognition of worn surface by using the friction coefficient signal in real time.