Stiffness And Deformation Of Asperities In ARough Contact

Abstract

In rough contacts the load is transmitted through the micro-contacts generated the interactions between the asperities. These micro-contacts are submitted by pressures and important stresses appear in the superficial layers close to the surface which lead to plastic deformation of the asperities. In our experimental work, we study the contact between a rough surface and a flat supphire. The samples used are Nickel electroformaging with quasi-sinusoidal roughness. The elastic and plastic parts of the deformation process of the roughness are determined, the experimental apparatus is composed of the loading system and an interferometric microscope in order to measure deformations. The values of the elastic deformation are compared to the theoretical results and the plastic ones with those obtained by using a profilometer coupled with the computer. Finally we deduce the asperity stiffness which are compared to those of the bodies. The results show the primary loading. The interacting asperities are loaded as well as the bodies. Then the elastic deformation and the stiffness are the main functions of the roughness' slope ( ratio of the asperity height to the wavelength ( Rt /1)). The asperity stiffness is very high compared to those of the bodies.