Study On The Flattening Behaviour Of Asperities In Contact Interface Of Rough Surfaces

Contact problem of rough surface with plastic deformation can be widely found in metal drawing. The surface morphology after plastic deformation is influenced by the original surface morphology, interface lubrication and the plastic deformation, and there are flattening, roughening and microwedge three kinds of mechanism in metal plastic deformation.In order to study the flattening behaviour of asperities in contact interface of rough surfaces, the influence of pressure, lubrication conditions and original surface topography on the surface topography variation of ball/plane contact was researched by experiment, Two kinds of random surfaces and one directional textured surface were used in the experiment. A series of ball/plane contact experiments under different pressures and different lubrication conditions were conducted by a spherical indenter. The surface of the specimens before and after the experiment were scanned by Talysurf CCI Lite Non-contact3D optical profiler respectively, and characterized by ISO25178. Finally the variation rate of the ISO25178parameters was calculated by comparing the related parameters before and after the experiment. The results show that:with the increase of the pressure, the flattening and roughening of workpiece surface happens. When the pressure is980N, the degree of the workpiece surface roughening is serious.Along with experiment, finite element method is used to analyze the flattening behaviour of asperities in contact interface of rough surfaces. The ball/plane contact modeling is found with the cosine shape asperities. The deformation condition of the asperities under different conditions of pressure and adhesive coefficient of friction are simulated respectively. The surface roughness and height of asperities are calculated, and finally, the relationship between surface morphology and pressure, adhesive coefficient of friction is summarized.