The paper describes a theoretical study of friction at elastic-plastic contact of rough surfaces in n-point asperity model framework and based on accurate finite element analysis of elastic-plastic deformation of single asperity contact. Plasticity index, a well-defined nondimensional parameter is used to study the prospective situations arising out of variation in material properties and surface roughness. Using practical values of material properties and surface roughness parameters, results are obtained for the behavior of applied load, friction force, and coefficient of friction as a function plasticity index and mean separation of surfaces. It is observed that with increase in amount of plastic deformation, the load required to be applied for maintaining a particular level of separation between contacting surfaces increases while the frictional force decreases. Coefficient of friction is independent of applied load in predominantly plastic domain of deformation but varies nonlinearly in other domains of deformation. Also, for the same applied load the coefficient of friction increases with increase in elastic deformation.

a b s t r a c tThe paper describes a theoretical study of adhesive friction at elasticeplastic contact of rough surfaces based on n-point asperity model. Well defined adhesion index and plasticity index are used to study the prospective situations arising out of variation in load, material properties, and surface roughness. Results are obtained for the behavior of friction force, applied load, and coefficient of friction for different combinations of adhesion index, plasticity index and mean separation of surfaces. The results obtained are in line with earlier models. It is observed that the tensile load required in maintaining a separation increases with increase in adhesion effect and extent of plastic deformation. Also coefficient of friction increases with adhesion effect.

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Abstract. The present work considers analysis of adhesive friction of rough surfaces using n-point asperity concept for statistical definition of surface roughness features, and accurate finite element analysis of elastic-plastic deformation of single asperity contact. The paper describes theoretical study in which whole range of deformation of an n-point asperity viz. from fully elastic, through elastic-plastic, to fully plastic is considered and the intermediate transition regime is treated analytically as well as numerically. Well defined adhesion index and plasticity index are used to study the prospective contact situations arising out of variation in material properties and surface roughness features. Using practical values of material properties and surface roughness parameters, results are obtained for normally applied load, friction force, and coefficient of friction. It is observed that the surfaces undergoing predominantly plastic type of deformation and having moderate to higher adhesion have constant coefficient of friction.

The paper describes a theoretical study of elastic-plastic adhesive contact of rough surfaces based on n-point asperity model and accurate finite element analysis (FEA) of elastic-plastic deformation of single asperity contact. The n-point asperity model developed by Hariri et al (2006) is integrated with the elastic-plastic model of . In this study an attempt is made to extend the work of by incorporating intermediate elastic-plastic regime of deformation. A large range of interference values ranging from fully elastic through elastic-plastic to fully plastic deformation of contacting asperities is considered. The effect of varying load and material parameters is analyzed in terms of well established adhesion index and plasticity index. A comparison between the present analysis with that of model shows significant difference in load–separation behaviour depending on combinations of mean separation, adhesion index and plasticity index.