  Contact analysis without adhesion is still a challenging problem, mainly
owing to the multiscale and self-fractal characteristics of rough surfaces. Up
to now, theories for analyzing contact behavior of rough surfaces in literature
can be generally categorized into two groups: the asperity-based Hertz contact
models initiated by Greenwood and Williamson (G-W model), which is shown more
accurate under small indentation distance, and the magnification-based pressure
diffusion theory initiated by Persson, which is shown to work well under full
contact conditions. The aim of this paper is to propose a theoretical model
that can effectively formulate the contact status of rough surfaces during the
entire compression process. This is achieved by integrating the idea of
magnification, or evolving resolution into an asperity representation of rough
surfaces, and a magnification-based multi-asperity model is thus established.
In the derived model, the originally complex contact problem is decomposed into
a family of sub-problems each defined on a morphologically simpler contact
islands. Benefiting from the explicit results given by Greenwood and
Williamson, the proposed method is relatively easy for numerical
implementation. Compared to other G-W type models, the proposed method has
especially shown its strength in the computation of the contact area. Moreover,
the G-W and Persson models are found well connected by the proposed method. For
its validation, the proposed model is well compared with existing numerical,
theoretical and experimental results. In particular, the proposed model has
shown its excellency through comparison with representative theoretical,
numerical and experimental data compiled in the contact challenge test by
Mueser et al.
