Simulation And Experimental Study On Friction And Wear Properties Of Combined Dynamic Seal Structure

Nowadays,combined dynamic seal structure has become one of key components in aerospace seal devices due to its excellent sealing performance,high reliability and long service life.However,it is very important to develop high-performance combined sealing structures due to severe challenges brought by harsh service environment with the rapid development in aerospace technology.Friction and wear are main factors to cause seal failure,on which has been paid great attention by application units and research scholars in recent years.Therefore,in-depth study on friction and wear characteristics and mechanism of combined dynamic seal structure can lay a foundation for improving service performance and service life of aerospace equipment.In this paper,friction and wear characteristics of typical VL combined dynamic seal structure and materials are investigated under complex conditions by theoretical analysis,numerical simulation and experimental research.Firstly,friction theory prediction model for seal materials is developed.A two-dimensional model of typical combined dynamic seal structure is developed by using finite element method.Based on this,a macro-micro pressure-length ratio for evaluating seal properties is proposed;Friction force theory model of rubber in sliding process is developed based on adhesion theory and hysteresis theory.Based on this,sliding friction force of rubber is analyzed,which lays a theoretical foundation for studying friction mechanism of rubber seal materials.Secondly,experimental study on friction and wear characteristics of sealing materials under complex conditions is carried out.A testing platform for the friction and wear characteristics of seal materials used in different temperatures is designed.Based on this,influence of sliding speed,load and temperature on friction properties of EPDM and PTFE are studied,which lays a foundation for simulation of combined dynamic seal structure;Evolution of surface morphologies of seal materials during wear process are studied by using DSX-510 optical digital microscope,then,friction and wear mechanism of seal materials in complex conditions are revealed.Then,mechanical properties of seal materials under oil conditions are studied,and characterization parameters of rough surface are obtained.Tensile/compression properties of seal materials under oil-free soaking and after phosphate hydraulic oil soaking are investigated by using High-low temperature tensile/compression tester,then influence of temperature,oil on stress-strain,weight change rate,tear elongation rate of seal materials are studied;Constitutive model of EPDM and PTFE are developed.Characteristic models of rough surface are developed based on the study of surface morphologies by using fractal theory and structure function method,which lays a foundation for next simulation on friction and wear properties of combined dynamic seal structure.Finally,macro-micro simulation model of dynamic seal structure in friction and wear process are developed based on constitutive model and rough surface characteristic model of seal materials.A fractal surface profile model of the combined dynamic seal structure is developed based on fractal characterization of micro-convex on rough surface.Then,wear finite element models of single micro-convex on seal structure surface are developed to study the influence of temperature,sliding displacement on microscopic friction and wear behavior.Finite element simulation model of VL seal structure is established to research macroscopic friction and wear properties of dynamic seal structure,which provides evidence for the development of high-performance combined seal structure.