Study On The Tribological Properties Of Surface Texture Of Rubber Strip On The Water Lubricated Bearing

Water lubricated rubber stern bearings are the important parts of underwater vehicles whoserubber quality is ofthe direct impacts on the stealth,security,performance and reliability of the vehicles.Although the rubber is of better damping effect,it is always easy to cause friction vibration and noise and reduce the mute level of the vehicles under low speed and heavy loads,especially at starting or stopping phases.In order to improve the tribological properties of both stern shaft and stern bearing,the rubber slats of water lubricated stern bearings were studied in the thesis.Both Finite element model of rubber surface texture and fluid model of water film were established expectedly with Workbech and Fluent software,the influence rules including surface texture shape,size,layout and other parameters on the tribological properties of rubber slats were studied,and the modal natural frequencies,modeofvibration and its influencing factors of surface texturing rubber slat analyzed,and the tribological properties of surface texturing rubber slat evaluated.The main research work and conclusions are as follows:(1)The research on the tribological properties of surface texturing rubber slat was made.Both finite element model and water film model were respectively established,and the fluid shear stress,friction resistance,water film pressure,and velocity distribution of the flow field were analyzed,and the calculation results of the surface texturing rubber slat were compared with smooth slat.The results show that under the same operating conditions,the water film shear stress distribution of surface texturing rubber slat is different from smooth one,and their friction resistance is 0.151 N and 0.158 N respectively,in other words the former is lower than the later.The water film pressure distribution range of both texture and smooth surfaces is 0.028~1914 Pa and 0.021~1480 Pa respectively.Compared with the later,the carrying capacities of water film of the former is higher.(2)The modal analysis on surface texturing rubber slats was finished.The modal models of both surface texturing and smooth rubber salts were respectively established to study the modal frequencies and modal shape The results show that the each frequency orderof surface texturing rubber stat is lower than one of the smooth slats,and their difference is from 5.9% to 13.8%.The higher of the modal order,the more smaller the natural frequency difference between two kinds of the rubber stats,but vibration shapes of two kinds of the rubber stats are basically unanimous.There is larger deformation on the third-order and fourth-order modes of surface texturing rubber stat and the main deformation region locates on the two ends of rubber slats.(3)The factors affecting friction resistance of surface texturing rubber slats were analyzed,such as the shape,size,arrangement,structure of surface texturing rubber slats,rubber performance parameters and operating conditions.With the increase of the elasticity modulus of rubber slats,both slat deformation and water film thickness are decreased,and the friction resistance is gradually decreased.Under the same textured surface area ratio and working conditions,the friction resistance of circular surface texturing rubber slat is less than the diamond texturing one.Surface texture plays an active role on reducing friction resistance of water film.If the surface texture had same diameter,the greater of the water film thickness,the greater of its friction resistance.The anti-drag performance of surface texture with a certain diameter and depth of the micro-pitted is better than the smooth bearing slats.