Simulation Study On Mixed Lubrication Wear Of Spherical Friction Pair

In the dry friction contact state,the relative motion of the friction pair is accompanied by a complex "heat stress wear" coupling behavior.The severe working conditions have higher requirements for the high temperature resistance and wear resistance of the friction pair.The research on the "heat stress wear" coupling problem of the friction pair in the dry friction sliding process can provide a theoretical basis for the life and reliability design of mechanical parts under severe working conditions.The development and technical application of lubrication theory provide an effective method to reduce friction and control wear.However,under extreme working conditions,the load is complex,which is affected by factors such as friction overheating,lubricant loss,wear degradation and so on.The friction pair has been in mixed lubrication service for a long time,and the wear condition is bad.The relative motion of the friction pair is accompanied by complex coupling behavior of lubrication and wear.Engineering applications have strict requirements on the structure,transmission efficiency and bearing capacity of friction pairs.The research on thermal stress wear coupling and hybrid lubrication wear coupling can provide theoretical basis and guidance for the life prediction and reliability design of friction pairs under severe working conditions.Firstly,this paper takes the drum brake of an armored vehicle as the research object.Considering that the influence of the change of temperature on the brake in the actual braking process can not be ignored,the classical Archard wear model can be modified by increasing the relationship between temperature and wear factor,which can effectively improve the accuracy of wear calculation.In the finite element thermal stress iterative solution process,the "complete coupling method" is used to continuously update the geometry of the brake wear surface,which continuously affects the calculation results of thermal stress,and more truly describes the complex coupling phenomenon of thermal stress wear in the braking process.Through simulation,the wear law of the brake under several typical working conditions is obtained.In addition,a mixed lubrication wear simulation method of spherical friction pair is designed in this paper.Combined with the wear experiment,the mixed lubrication wear mechanism and Tribological Properties of spherical friction pair are studied.The sliding process of spherical friction pair is accompanied by various mechanical behaviors(hydrodynamic bearing,elastic deformation of friction pair surface,rough contact surface of friction pair,micro convex contact,contact surface wear,etc.).Based on the control equation of mechanical behavior,the mixed lubrication wear model of spherical friction pair is established.Considering the actual working condition of spherical friction pair,the initial load condition of the model is modified to the sliding contact pressure of spherical friction pair.According to the influence of normal load,tangential friction and wear on contact pressure,the contact problem of spherical friction pair is transformed into a constrained quadratic programming problem.The conjugate gradient method is used to solve the sliding contact pressure distribution.The continuous influence of wear is characterized by the equivalent radius of curvature of the contact surface profile of friction pair.Finally,the mixed lubrication wear experiment and simulation analysis of spherical friction pair are carried out,and the variation laws of contact stress,friction coefficient,wear depth and wear width under the condition of mixed lubrication are discussed.