Molecular Dynamics Simulation Of Microscopic Contact Behavior And Friction Properties Of Natural Rubber

Natural rubber is a commonly used polymer material and is widely used in industrial engineering,machinery,aerospace,marine and military fields.However,the service life of rubber materials largely limits the application and development of rubber materials,and the friction properties of rubber materials are important factors that affect their service life.Therefore,the friction properties of rubber materials have received more and more attention.Traditional research methods are based on experiments.Because of the limited scale effect,experimental methods can only draw relatively wide results in the macroscopic state.With the development of science and technology,the application of materials is changing,and more and more.Rubber materials have been used in the production of micro devices.In recent years,with the development of computer science and technology,the use of computer simulation methods to study the material properties has become a trend.Molecular dynamics methods were used to qualitatively investigate the microscopic contact behavior and friction properties of natural rubber from the molecular level by computer simulation.(1)Using the molecular simulation software Material Studio(MS)to establish a natural rubber model,and optimize the model structure,using the LAMMPS software to do a secondary treatment of the established model,a natural rubber glass transition temperature of 221 K was obtained by the simulation,the value close to the experimental value.Which shows the feasibility of the simulation method and the selected potential function parameters are more accurate.Understanding the method and process of molecular dynamics simulation through the simulation of glass transition temperature.(2)The process of pressing the rubber substrate by the probe was simulated by bombarding the rubber substrate with the initial velocity applied to the probe,and the simulation data was collected to discuss the change of the natural rubber motion state to analyze the mechanical properties of the natural rubber.The effects of the degree of polymerization of the rubber molecular chains and the ambient temperature on the press contact process of natural rubber were studied.The results show that the degree of rubber molecular chain polymerization has an effect on the mechanical properties of rubber.When the degree of molecular chain polymerization is large,during the impact of the probe,the velocity decreases rapidly,the displacement of the probe inside the rubber substrate is small,the time of the probe pressing process is short,and the mechanical properties of the rubber material are significantly enhanced.The influence of ambient temperature on the pressing process shows different trends.Below the glass transition temperature,natural rubber increases its ability to withstand external forces as the temperature increases.Above the glass transition temperature,as the temperature increases,the hardness of natural rubber decreases and also the resistance of external forces.Analysis of the rubber base atomic configuration during pressing shows that with increasing temperature,the elastic properties of natural rubber increase.(3)Molecular dynamics method was used to simulate the friction process between the probe and natural rubber.The influence of ambient temperature and probe sliding speed on the friction process of natural rubber was mainly discussed.The results show that the frictional force increases with the increase of temperature during the sliding process,and the sliding friction decreases with the increase of the temperature above the glass transition temperature.The influence of temperature on the sliding friction coefficient is basically the same as that of the friction force.In the glass state,the friction coefficient increases with increasing temperature,and when the temperature increases above the glass transition temperature,the friction coefficient increases.The temperature increases and decreases.The influence of ambient temperature on the temperature change of the contact area is shown under normal conditions.When the ambient temperature is low,the temperature change rate of the contact area is large,and when the ambient temperature is high,the temperature change rate of the contact area is small.When the sliding speed changes,the frictional force,the friction coefficient,and the temperature of the contact area increase as the sliding speed increases.