A microcontact model developed for sphere- and cylinder-based fractal bodies in contact with a rigid flat surface

The present study examines sphere- and cylinder-based fractal bodies in contact with a smooth and rigid flat surface. The generalized Weierstrass–Mandelbrot function (the W–M function) is employed in combination with the radius–vector function method (the (r, θ) method) to derive the formulae of fractal surface asperities formed on a smooth spherical surface and a smooth cylindrical surface. The size distribution functions used to calculate the contact load and the real contact area of an apparent area were derived for the three deformation regimes of microcontacts. The non-Gaussian probability density functions for two contact forms (cylindrical and spherical) were developed by combining the probability density functions developed for all small elements in the contact area using the superposition technique. In the present model, the deformation behavior demonstrated in the elastic, elastoplastic, and fully plastic deformation regimes is consistent with that described by classical (statistical) theories. Both the contact load and the real contact area results predicted by the present fractal model at various minimum separations show very good agreement with the results obtained using the statistical method. However, the results also exhibited properties very different from the results predicted by the unmodified fractal model, which showed the microcontact behavior demonstrated in the three deformation regimes to be exactly opposite to that predicted by the classical theories.