| Joint surfaces exist in various mechanical structures,so it is particularly important to study the contact characteristics of joint surfaces.As one of the contact characteristics of joint surfaces,the static friction coefficient of joint surfaces has an important influence on the working performance of machine tools and other mechanical equipment.When the tangential load applied on joint surfaces exceeds its maximum static friction force,the joint surfaces will slip in the tangential direction,resulting in the failure of the mechanical structure connection.Therefore,it is of great theoretical and practical significance to study the static friction coefficient of the joint surfaces.Now,all presented models for static friction factor of joint surfaces do not consider asperity interaction.Based on the statistical theory and scale correlation fractal theory of joint surfaces respectively,the statistical model and scale correlation fractal model of static friction factor of joint surfaces considering asperity interaction are established.The influences of asperity interaction and relevant parameters of joint surfaces on the static friction coefficient of joint surfaces are analyzed with the established models’ simulation.And the models were verified by experimental datum.The main research works are as follows:(1)A statistical model of the static friction factor of joint surfaces considering asperity interaction is established.Through the simulation analysis of the model,it is found that the static friction coefficient of joint surfaces is greater after considering asperity interaction than before.Comparing with the previous models and experimental datum,the calculation results of the model are closer to the experimental datum,which verifies its correctness.(2)A scale correlation fractal model of the static friction factor of joint surfaces considering asperity interaction is proposed.Through the simulation analysis of the model,it is found that the static friction coefficient of joint surfaces is also greater after considering asperity interaction than before,which is consistent with the statistical model proposed above.Comparing with the scale correlation fractal model of static friction factor of joint surfaces without considering asperity interaction,the presented scale correlation fractal model is closer to the experimental datum,and the correctness of the model is verified.(3)Several conclusions are obtained from the simulation analysis of the static friction factor statistical model of joint surfaces considering asperity interaction.With the decrease of the average distance between joint surfaces and the increase of the normal contact load,the static friction coefficient of joint surfaces decreases.With the increase of the root mean square of joint surfaces profile and the plasticity index of joint material,the static friction coefficient of joint surfaces decreases.With the decrease of the average distance between joint surfaces,the increase of normal contact load and the plasticity index of joint surfaces,the influence of asperity interaction on the static friction coefficient of joint surfaces decreases gradually.(4)Several conclusions are obtained from the simulation analysis of the scale correlation fractal model of the static friction factor of joint surfaces considering asperity interaction.With the increase of the fractal dimension of joint surfaces,the decrease of the fractal scale coefficient of joint surfaces and the plasticity index of joint surfaces’ material,the static friction coefficient of joint surfaces increases gradually.With the decrease of the fractal dimension of joint surfaces,the increase of the fractal scale coefficient of joint surfaces and the increase of the plasticity index of joint surfaces material,the influence of asperity interaction on the static friction coefficient of the interface de-creases gradually. |
PDF Full Text Request