Fractal models in tribology: A critical review

A detailed review of various fractal models used in tribology is presented. The analysis of the models is based on the use of the Cantor–Borodich (C_B) profile and its modifications. This profile and related models may be studied analytically and, therefore, they provide us with tools for rigorous analysis of fractal approaches to description of surface roughness and corresponding contact problems. In turn, this allows us to present a critical review of current fractal approaches to tribology. It will be demonstrated that fractal dimension alone cannot give a full description of surface roughness, however, some of these models may reflect the multilevel hierarchical structure of real surface roughness. This review helps to avoid the repetition of common erroneous statements about the use of fractal concepts in tribology.