微织构排布方式对水润滑轴承启停过程摩擦学性能的影响

Effect of Microtexture Arrangement on Tribological Properties of Water-lubricated Bearings During Start-stop Process

梯度排布微织构在提升水润滑轴承摩擦学性能方面具有显著效果,然而梯度排布微织构在水润滑轴承中的应用仍缺乏系统性研究。为了探究梯度排布微织构对水润滑轴承启停过程摩擦学性能的影响,基于Greenwood-Tripp微凸体接触模型、Archard磨损模型求解轴瓦表面的磨损量。通过CFT-I材料表面性能综合测试仪对CNC雕刻机加工的织构化表面进行水润滑条件下的摩擦学试验研究。针对光滑、单一圆形织构、圆形与三角形以轴向交错平行■和周向交错平行分布(1212)方式梯度排布的表面,测量各个表面的磨损量和摩擦因数。通过立体显微镜、扫描电子显微镜对摩擦磨损试验前后的表面形貌和摩擦因数进行分析。数值模拟和试验结果显示,与光滑表面和单一织构化表面相比,梯度排布微织构化表面磨损量和摩擦因数显著降低;圆形与三角形以■方式的梯度排布微织构化表面摩擦学性能最佳,接触表面磨损量最小、表面摩擦因数最低。梯度排布微织构在流体润滑过程中相互影响,可以起到提高轴承表面举升力,减少表面接触,降低表面磨损和摩擦因数的作用。研究不同形状、排布方式下梯度排布微织构化表面的磨损量和摩擦因数的变化规律,可为舰船装备水润滑轴承研制阶段主动设计提供理论基础。

Water-lubricated bearings are key components of the trailing axis systems of naval equipment and are widely used in ship axis systems.Bearings are often subjected to unbalanced forces,such as inertial forces caused by the weight of the propeller and additional forces generated by the deformation of the vessel body during its operation.These harsh working conditions would result in poor lubrication of the bearings and cause severe friction and wear.The gradient-arranged microtexture has a significant effect on improving the tribological performance of water-lubricated bearings,which is significant for improving the bearing lubrication and load-bearing performance and reducing wear.However,systematic research on the application of gradient-arranged microtextures in water-lubricated bearings is lacking.To evaluate the effect of the gradient-arranged texture on the tribological performance of water-lubricated bearings during the start-stop process,the surface wear of the shaft shank is solved based on the Greenwood-Tripp micro-convex body contact model and the Archard wear model.The effect of the microtextured arrangement on the tribological performance of the water-lubricated bearings during the start-stop process is analyzed.The tribological properties of water-lubricated gradient-arranged textured surfaces are evaluated using the CFT-I material surface property comprehensive tester,which verifies the results of the numerical calculations.The gradient-arranged textured surfaces are manufactured by the computer numerical control engraving machine.The effects of the microtextured depth and circumferential spacing on the average wear of water-lubricated bearing surfaces are calculated using numerical simulations.The optimal microtextured depth and circumferential spacing are selected to design the microtextured arrangement based on the numerical simulation results.The effects of the microtexture gradient-arranged on the average wear of the water-lubricated bearing surfaces are also calculated.The wear amounts and friction factors of each surface are measured for the smooth,single-circular texture,circular and triangular surfaces arranged in a gradient of axially staggered parallel(■),and circumferentially staggered parallel distribution(1212).The morphology and friction factor of the surfaces before and after the frictional wear experiments are analyzed using stereo microscopy and scanning electron microscopy.The effects of the gradient-arranged microtexture on the surface morphology and friction factor of the water-lubricated bearings are analyzed.The numerical simulation results showed that the surface wear amounts of the gradient-arranged microtexture were significantly decreased compared with those of the smooth and single-texture surfaces.The best tribological performance of the gradient-arranged microtextured surfaces with the circular composite triangle in the form of ■ had the lowest wear amount at the contact surface.The experimental results showed that the friction factor of the gradient-arranged microtextured surfaces was more than 40%lower than that of smooth and single-textured surfaces.Similarly,the surface with circular composite triangles arranged in the form of an 121 gradient microtexture had the lowest friction factor.There were evident water film pressure convergence zones on the bearing surface under water-lubricated conditions,which could enhance the water film lifting force and generate dynamic pressure effect.The gradient-arranged microtextures interact with each other in the fluid lubrication process to enhance the lifting force on the bearing surface,which plays a role in reducing the surface wear and lowering the friction factor of the contact surface.Thus,an appropriate gradient-arranged microtexture can significantly improve the tribological performance of bearing surfaces.Increasing the convergence zone of the surface water film pressure,improving the surface lifting force,and reducing the surface contact,surface friction factor,and surface wear should be considered when designing the surface micro-texture.The study of the influence of different shapes and arrangements of gradient-arranged microtexture-structured surfaces on the wear amount and friction factor can provide a theoretical basis for the active design of water-lubricated bearings in the development stage of naval equipment.