In the present study, the formulas for the asperity contact loads $(Fec$ and $Fpc)$ corresponding to the critical interferences at the inception of elastoplastic and fully plastic deformations are employed to establish their relation with the ratio of these two critical interferences $(δec$ and $δpc).$ The critical interference ratio $δpc/δec$ can thus be expressed as a function of the critical contact load ratio, $Fpc/Fec,$ whose value was obtained from the experimental results of metallic materials. The interference $δpc$ corresponding to the inception of fully plastic deformation can thus be determined. The dimensionless analyses of asperity contact area, average contact pressure, and contact load in the elastic and fully plastic regime reveals that these parameters in the elastoplastic regime can be expressed in power form and to be as a function of dimensionless interference $δ/δec.$ The coefficients and exponents of the power form expressions can be determined by the boundary conditions set at the two ends of this regime. Four models are proposed in this study to compare the contact behaviors in the elastoplastic regime. The applications in contact of rough surfaces are also presented and discussed.

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