Study On Microscopic Eiasto-plastic Contact Characteristics Of Mechanical Joints

The simulation of real contact between two mechanical parts plays an important role in understanding tribology phenomena such as friction,abrasion,adhesion,electricity,heat conduction and lubrication.Therefore,the micro-contact between mechanical bonding surfaces has always been the focus of domestic and foreign scholars.In this thesis,a numerical contact model is established based on the fast Fourier algorithm and conjugate gradient method to study the micro-elastoplastic contact characteristics between mechanical bonding surfaces.In order to simplify the calculation,the micro-convex peaks on the rough surface must be assumed as an ideal shape in the study of the contact characteristics between the mechanical surfaces,and the ellipsoidal rough peak model is usually the best fit for the real situation.The influence of tangential force and ellipsoid rate on contact pressure,Mises stress,equivalent plastic strain and residual stress in contact process is studied by using the numerical model to study the contact characteristics between the rigid ellipsoid and the elastoplastic half plane.In the process of sliding contact,due to friction,there will be friction heat generation,the numerical method is used to calculate the thermal coupling contact in the sliding process,and the influence of temperature on the contact characteristic parameters during the sliding process is studied.In order to verify the correctness of the numerical model calculation results,the finite element method is used to verify the results,the maximum error of the contact characteristic parameters of the two algorithms is not more than 10%,and the variation trend of contact characteristic parameters is identical.In the study of surface-plane contact characteristics,the rough surface of different roughness values is established by reverse modeling method.The contact characteristics between rough surface and rigid smooth surface obtained by reverse modeling are studied by using the finite element method.In the surface-plane contact study,the transient nonlinear statics analysis is carried out firstly,the influence of different roughness values on the contact characteristic parameters is analyzed,and the variation trend of the contact characteristic parameters under the same roughness value and different normal load is studied.Secondly,the thermal coupling analysis is carried out,with roughness value Ra=3.2 turning rough surface and smooth surface as the research object,the uniform load is applied to the rough surface,and the 20m/s velocity is slid along the x axis to extract the maximum value of each contact characteristic parameter in the sliding time 20?s,to study the variation rule of the contact parameters in the process of thermal coupling contact.It can be known that the heat flux is related to the contact pressure,sliding velocity and the friction coefficient between the contact interfaces during the contact process.This thesis also studies the influence of these parameters on the maximum temperature of the contact interface during the contact process.Finally,using the established numerical model calculates the surface to surface contact characteristic parameters,and obtains the cloud diagrams of various characteristic parameters.Comparing the numerical computation cloud map with the finite element simulation cloud map,it is found that the cloud maps obtained by the two methods have basically the same change trend,and error calculation and analysis are performed on the maximum values of the various characteristic parameters.The error of the results obtained by the two methods is less than 10%,which verifies the accuracy of the numerical calculation results.