Abstract
Proper methods and models for mechanical analysis of rough surface can improve the theory of surface contact. When the topography parameters of two rough surfaces are similar, the contact should be considered shoulder-shoulder rather than top-top. Based on shoulder-shoulder contact and fractal characteristics, the geometric model for asperity and contact mechanics model for rough surfaces are established, and the deformation of asperity, the real contact area and contact load of sealing surface are discussed. The effects of contact pressure p and topography parameters (fractal dimension D and fractal roughness G) on the variation of porosity and contact area ratio Ar/A0 are achieved. Results show that with the increase of p, larger D and smaller G corresponds to larger initial porosity but faster and larger decrease of porosity; with the increment of D, porosity increases first and then decreases, and smaller G corresponds to larger porosity reduction; as G becomes bigger, porosity increases, and larger D corresponds to larger porosity difference and change. With the addition of p, Ar/A0 increases, and the variation of Ar/A0 is closer to linearity and less at smaller D and larger G; with the increase of D, Ar/A0 increases gradually, and the growth rate is bigger at smaller G and bigger p; as G becomes bigger, Ar/A0 declines, and it declines more gently at smaller D and p. The influence of D on Ar/A0 is greater than that of G. The results can provide the theoretical basis for the design of sealing surfaces and the research of sealing or lubrication technologies of rough surfaces.
Highlights
At a microscopic level, the rough surface consists of numerous asperities of different sizes which may be caused by form errors, waviness and roughness
Mechanical analysis of rough surface is the main content of surface contact theory, which involves real contact area, contact pressure and the relationship between them
Porosity φ is the proportion of pore volume in total volume, subscript r-f is the contact between rough and flat surfaces, and r-r is the contact between two rough surfaces
Summary
The rough surface consists of numerous asperities of different sizes which may be caused by form errors, waviness and roughness. Based on the GW statistical model and probability density function of height distribution for asperity, Xiao [20] established the total stiffness model of rough surface contact by considering the contact state of elastic, elastic-plastic and purely plastic deformation. Majumdar and Bhushan [22] established the rough surface contact model (M-B model) based on fractal theory for the first time They deduced the elastic and plastic contact deformation of the single asperity, but they did not consider the elastic-plastic contact problem. On these, thefor effects contact are established; and topography the deformation of asperity, thedimension real contactDarea contact load pressure and surface parameters Surface topography parameters (fractal dimension D and fractal roughness G) on the contactofarea of sealing surface are studied
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