Study On Dynamic Wetting Behavior And Tribological Property Of Bioinspired Rubber Surface With Microtextured And Wettablity Gradient

In the face of the more and more stringent performance requirements of marine propulsion system and shaftless propulsion system for water-lubricated bearing rubber material technology in the aspects of low noise,high reliability,long life and low runout,it is more urgent to establish a multidisciplinary collaborative innovation theory system of rubber material tribology,materials science and reliability engineering under dynamic service conditions.The innovative design and method of rubber bearing materials have an important influence on lubrication performance,working reliability and service life of water-lubricated bearings.Through basic theory and experiment,the dynamic wetting,dynamic lubrication performance and tribological characteristics of rubber matrix material are studied,which can provide a powerful theoretical analysis tool for the actively optimized design of tribological performance of water-lubricated rubber bearing system.In this paper,aiming at the basic theory and the modeling of dynamic wetting and tribological characteristics of the rubber-based surface,the interface wettability and the lubrication characteristics of bioinspired rubber-based surface with microtexture and wettability gradient were studied by experimental and numerical simulation methods.The influence of wettability gradient and surface microtexture on the bioinspired surface wetting characteristics and tribological behavior of rubber-based was revealed law.The main contents of this paper are as follows:(1)Study on wettability gradient,water condensation and water collection of the bioinspired surface.Inspired by the characteristics of water collecting from cactus and desert beetle,the bioinspired wettability gradient surface was constructed by ultraviolet ozone irradiation.The directional transmission of droplets,the condensation of water droplets on the surface and the dynamic transport process of water droplets were studied.The corresponding theoretical model was established and the directional transmission mechanism of water droplets has analyzed.The structure and parameters of the surface were optimized by condensation test,and the optimized bioinspired wettability gradient surface was obtained.(2)Study on dynamic wetting of bioinspired surface with microtexture and wettability gradient.The rubber surface with regular microgroove structure and wettability gradient was prepared by ultraviolet ozone irradiation,curing press treatment and femtosecond laser processing.The influence rule and mechanism of partial microgroove and overall microgroove on surface wettability were studied.The influence rule of microgroove type and microgroove depth on the dynamic wettability of surface was analyzed.According to the distribution of wettability gradient,a high-speed camera was used,the dynamic behavior of the water droplet was analyzed by the impact of the water droplet on the surface with microtexture and wettability gradient.(3)Study on tribological characteristics of bioinspired surface with microtexture and wettability gradient.The surface with microtexture and wettability gradient was studied by ball-on-disk friction test.The change rule of tribological properties was caused by surface texture and wettability of rubber material was explored.The effects of rotating speed,load,microgroove type and wettability gradient distribution on the tribological properties of rubber surface were studied.Based on the numerical simulation,the typical surfaces of different microgroove types are constructed,and the influence factors such as microgroove angle,depth and wettability gradient distribution are considered.The variation laws of surface lubrication characteristics such as distribution of hydrodynamic pressure,slip velocity and flow velocity are analyzed.The lubrication mechanism of the surface with microgrooves and wettability gradient is indirectly discussed,and the experimental results are verified with the simulation results.(4)Numercial simulation study of bioinspired rubber with microtexture and wettability gradient in water-lubricated bearings.Based on the limit shear stress model,the Reynolds equation considering the microtexture and wettability gradient was deduced,and the application of rubber materials in water-lubricated rubber bearings was comprehensively considered.The distribution of hydrodynamic pressure,water film thickness,slip velocity and flow velocity of water-lubricated rubber bearings were analyzed.The style,angle,depth,eccentricity raito and wettability gradient of microgrooves were studied,and the lubrication mechanism of water-lubricated rubber bearing with microgrooves and wettability gradient was revealed.