| In this paper,several friction research methods were investigated,and we found that the main study focued on experimental researches at present.Numerical simulation is mainly limited in finite element simulation method.Therefore,we use the principle of movable cellular automata method to compile a simulation program for friction materials,and study the influence of friction velocity,friction pressure and copper content on the material friction coefficient.We also explore the the changing rules of the third body particles on friction surface.(1)We use Matlab to compile a calculation program based on the mobile cellular automata method.Firstly,according to Newtone Euler's motion equation,the motion law of each cell are given.Secondly,the connection states between the cells are determined as:connection(resistence tensile stress,bound),contact(non-resistance tensile stress,unbound),non-connection,and these kinds of connection state calculation methods are given.Finally,the constitutive equation of the cells are considered,and the equivalent stress and equivalent strain of the cells are obtained.The correcting algorithm are used to correct the interaction forces of the cells when the cells are in a plastic state.(2)We use Matlab to compile a program for predicting the size of the inter-cells connection.The sintered particles are equivalent to the cells calculated by the mobile cellular automata method.In order to determine the connection area between the sintered particles,we establish a calculation program for predicting the size of the sintered neck based on the sintering theory of metal particles.The results of the calculation program reveal that the sintered neck size increase with increasing of time.(3)The changing law of the friction coefficient of the friction material and the evolution law of the third body are obtained by the mobile cellular automata calculation program,when the third body of friction material is assumed as pure copper and copper-graphite composite.When the third body is assumed as pure copper,the simulation results show that the oscillation of the nominal friction coefficient increase with the increase of friction speed,but the average friction coefficient almost keep a constant value with the increase of friction speed or friction pressure.When the third body is assumed as copper-graphite composite,the results show that the average friction coefficient of the material decreased with the decrease of the copper content,and the increase of the graphite content can reduce the friction coefficient and reduce the oscillation amplitude of the friction coefficient. |
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