Analysis And Optimization Of Transient Wear And Mixed Lubrication Performance Of Microgroove Water-Lubricated Bearing

Water-lubricated bearings systems are widely used in the transmission systems of ships,submarines,underwater robots and shaftless pump.Conduct in-depth research for the transient wear behavior and mixed lubrication phenomenon of bearing system under complex operating conditions.The micro-grooved water-lubricated bearing system transient wear-mixed lubrication theoretical model of multi-mechanism and strong coupling relationship is established,which adopting the method of surface texture,and integrated application of surface engineering,lubrication theory,fluid mechanics,contact mechanics,material mechanics and other disciplines.A comprehensive research on dynamic tribology performances and optimization of microgroove water-lubricated bearing system under multi-field and multi-factor conditions is carried out to provide a guiding scheme for the improvement of the comprehensive performance of the bearing system in service conditions.Furthermore,the wear aggravation of micro-groove waterlubricated bearing system due to the rotor misaligned under running state is fully considered.The shaft profile design method is proposed to provide the optimum scheme for the bearing system under complex operation conditions and different structural parameters.At the same time,a series of equivalence experiments on the comprehensive friction and wear properties of micro-grooved water-lubricated bearing materials are carried out,which effectively verified the correctness and scientificity of the theoretical model and optimization design.This research method has great theoretical and engineering significance for improving the dynamic tribology performances and service life of water-lubricated bearing transmission system.The main research contents of this thesis are as follows:(1)After the comprehensive analysis of the present situation of surface texture research,and the feasibility of micro-groove structure design on the surface of waterlubricated bearing is demonstrated.Established the microgroove water-lubricated bearing transient wear and mixed lubrication coupling model under the dynamic service condition,the theory model comprehensive considering the behavior,water film pressure performance and transient mixed elasto-hydrodynamic lubrication mechanism of bearing system,and the mapping relationship and action mechanism among dynamic wear,contact and lubrication of the interface of the micro-grooved water-lubricated bearing during operation are effectively revealed.(2)Based on the established dynamic wear-mixed lubrication coupling theoretical model of micro-grooved water-lubricated bearing system,the time-varying evolution law of wear characteristics,contact behavior,hydrodynamic pressure performance and bearing capacity of the bearing system during service was fully evaluated.The influences of microgroove structure parameters and distribution on dynamic tribology,including groove type,angle,morphology,number,area ratio and position,are studied comprehensively and deeply.The optimal design method for the microgroove waterlubricated bearing system under multi-field and multi-parameter conditions is presented,which provides theoretical guidance for the enhancement of the system anti-wear performance and the improvement of interface lubrication ability.(3)Based on the optimal design of microgroove water-lubricated bearing,the influence of bearing structure parameters and bearing surface characteristics parameters on the prediction of dynamic tribology performance are analyzed.The important evaluation indexes representing wear behaviors,such as time-varying friction fatigue wear characteristic,rough peak elastic-plastic contact,and representing transient mixed lubrication performance,such as transient water film thickness,fluid dynamic pressure and load carrying capacity,are studied from multiple perspectives.In order to provide effective evaluation and guidance for structural design and material selection of microgrooved water-lubricated bearings.(4)The rotor misaligned of microgroove water-lubricated bearing system caused by excessive external load is investigated.Through the prediction and analysis of the dynamic tribological performance of the system under the rotor misaligned state,a method of rotor profile design for microgroove water-lubricated bearing system is proposed to fully evaluate the influence of profile design on the transient wear and mixed lubrication performance.The optimal design scheme of microgroove water-lubricated bearing system under the influence of misaligned is provided,which considered complex operating conditions and different bearing system structures.The presented study provides a feasible method for enhancing the wear reduction and improving the service life of the bearing system.(5)A series of equivalence verification experiments of micro-grooved waterlubricated bearing materials are carried out on a friction and wear tester.The microgrooves on the specimens are fabricated by Laser engraving machine.Experimental research is carried out on the design scheme of micro-grooves and the transient friction and wear performances of bearing materials under water lubricated condition.The correctness and scientificity of the dynamic wear-mixed lubrication coupling theoretical model of micro-grooved water-lubricated bearing presented in this paper and the rationality and effectiveness of the grooved design scheme are verified by compared experimental results with theoretical results.