Multi-field Coupling And Friction-induced Noise Analysis Of Water Lubricated Rubber Bearing

The dissertation is based on the project “Research of the vibration and noise mechanism and reliability on the large-size water lubricated rubber bearing” from National Natural Science Foundation of China(Grant No.51175521)and “Innovative design theories and methods of XXX with high reliability and low friction-induced noise” from National Defense Research Project(B14XXX).In order to further improve load capacity and noise suppression ability of water lubricated bearing,mixed lubrication model introducing high load,low speed,axial flow,shaft deflection and other complex working conditions was established by combining theories from tribology,hydrodynamics,contact mechanics and thermodynamics.The influence of working conditions,rubber bushing design and geometric design were analyzed individually.The performance of water lubricated rubber bearing was studied under fully lubricated conditions and insufficient lubricated conditions experimentally to study its mechanism under full film lubrication and mixed lubrication.The noise composition and the mechanism of micro friction of water lubricated rubber bearing under insufficient lubricated condition were further analyzed and complex eigenvalue analysis were adopted to solve its unstable modes.These results provided reliable data to develop water lubricated rubber bearing with high reliability,low friction and low noise along with its design theory,methods and technology.The specific research points were as follows:1)A numerical model was established considering multi factors of water lubricated rubber bearing,such as surface roughness,the number of grooves and frictional heat.Critical parameters to evaluate the performance of water lubricated rubber bearing under complex working conditions such as load distribution,temperature distribution,deformation distribution and film thickness distribution were calculated.These work provided theoretical support to optimize the performance of water lubricated rubber bearing in the future.2)The numerical model was adopted to evaluate the performance of water lubricated rubber bearing and the influence of load,speed,elastic modulus and thickness of rubber were also thoroughly analyzed.The results indicated that the performance of water lubricated bearing can be improved by altering working conditions or design parameters.However water lubricated bearing always work in the mixed lubricated region,and its stress concentrated on the bottom stave,with a thin distribution in circumferential direction and an asymmetry distribution in axial direction.3)Performance of water lubricated rubber bearing was examined experimentally under full lubricant supply and insufficient supply,along with its surface wear and noise composition.The results indicated that the friction coefficient of water lubricated rubber bearing would only increase sharply under insufficient lubricant supply,with serve surface wear and noise generation.The composition of such noise mainly located near 4000 Hz,and could be affected by multi external factors.4)Friction experiment was conducted on rubber under full lubricant supply and insufficient supply and the worn surfaces of the rubber were observed using SEM to investigate the wear mechanism of rubber and its relationship with friction induced noise.The results indicated that the micro stick-slip movement created regular ripple wear pattern on the rubber surface and was the fundamental cause of friction-induced noise.The composition of friction-induced noise can be solved by complex eigenvalue analysis with appreciated friction coefficient.