Contact Analysis Of Interface With 3-D Real Rough Multi-scale Surface Using Element Finite Method

The real contact characteristics of interface for machine tool play an important role in analyzing performance of the heat transfer,friction,wear and lubrication and so on.At designation stage of machine tool,the real surface topographic data are adopted to build up rough surface topography of parts,analyze surface characteristics and performance of interface,which has important theoretical and practical significance to enhance design quality of parts and machine tool.This thesis mainly focused on several following aspects:(1)Using three-dimensional topography instrument measures surface profile of two grinded parts with different materials and different roughness to obtain three-dimensional topography data which are multi-scale decomposed with two-dimensional wavelet transformation.The morphological characterization of multi-scale decomposition surface is implemented to assess surface morphological features objectively,which is very significant to control the surface quality.(2)Two kinds of solid modeling methods of 3-D real rough surface with APDL in ANSYS software are proposed:moving nodes method and the bottom-up method.The corresponding basic mathematical model of contact problems,the finite element equation and solution are derived.Points for attention during exploring solutions of equations and their settlements are given.(3)A rigid-flexible contact model based on three dimensional solid with real rough surface is established.The relationships between the real contact area and applied load,the normal displacement and the normal stress are obtained after the contact status of ground interfaces of steel 45 as well as HT200 involving different scales and different roughness is investigated.The analysis results show that the real contact area,normal displacement and normal stress nonlinearly increase with the enhancement of load.Moreover,the more smooth the surface,the greater the real contact area,the smaller the normal displacement and the normal stress under the other conditions being the same.(4)The experiment of the real contact area of mechanical interface is accomplished.The experimental result and the simulation result with ANSYS are compared and both results are basically identical.The experiment of the normal displacement is carried out.Comparison between the finite element simulation results and the experimental results shows that both of them agree with each other reasonably.This study would be significant to guide some work in engineering application,such as improving the surface contact characteristics,predicting the friction and wear of practical machine system quantificationally,and developing high-performance frictional materials and final processing for initial surface of friction pairs,etc.