The Characteristic Fractal Parameter for the Characterization of Rough Surfaces

The issues about the characterization of rough surfaces are always of concern to tribologist. Because the statistical parameters used conventionally are not ideal to characterize rough surfaces, it is very necessary to investigate the new characterization methods and characterization parameters. In this paper, the fractal geometry is applied, and a roughness parameter called the characteristic fractal parameter τ* is put forth by combining fractal dimension D and scale coefficient C. Its definition, geometric meaning and mathematical express are given. Four surfaces with different roughness formed by turning, milling, grinding and sandpaper polishing machining are characterized with the characteristic fractal parameter τ*. And the results of characterizing these surfaces are compared with that of R_a. It is proved that the characteristic fractal parameter is not only more objective but also more sensitive to characterize rough surfaces than the conventional characterization parameter R_a.