表面织构及供油量对润滑性能影响的建模分析

目的研究不同供油条件下织构表面的润滑性能。方法首先,建立考虑表面织构的乏油润滑模型,求解修正雷诺方程获得乏油工况下考虑织构表面的润滑油膜厚度以及压力分布。然后,依据求得的润滑油膜厚度判断计算域内各点润滑状态,通过接触压力及油膜厚度分别计算边界润滑、混合润滑以及流体润滑状态下的切应力,并积分求得摩擦力进而得到摩擦系数。结果模拟了供油层厚度为50~500 nm以及充分供油条件下三种织构的润滑行为,获得了不同润滑状态下表面织构的摩擦系数。速度为0.1 m/s时,供油量对接触区油膜厚度的影响较小,不同润滑状态下织构表现出不同的润滑性能。速度为0.2 m/s时,供油层厚度对油膜厚度的影响较大,随着供油层厚度的增大,膜厚明显增加,摩擦系数在供油层厚度为200 nm时最小。结论接触副处于流体润滑状态时,织构表面不具有减摩效果。接触副处于边界润滑状态时,织构表面具有减摩效果,并且织构较密时,摩擦系数较小。接触副处于混合润滑状态时,织构过于稀疏或密集时均不具有减摩效果,但是合理分布的织构具有减摩效果。

Effect of Surface Texture and Oil Supply on Lubricating Performance Based on Modeling

The work aims to study lubricating property of texture surface under different oil supply conditions. Firstly, starvation lubrication model allowing for surface texture was established, and then the oil film thickness and pressure distribution of texture surface under starvation working conditions could be obtained by solving the modified Reynolds equation. Secondly, lubrication state at each point in contact area was determined based upon the film thickness, and shear stress under boundary lubrication, mixed lubrication and hydrodynamic lubrication was calculated based upon contact pressure and film thickness, friction coefficient was obtained by integrating frictional force. The lubricating behavior of three textured surfaces was simulated with the oil supply thickness of 50~500 nm and under full supply conditions to obtain friction coefficient of surface textures under different lubrication conditions. At the speed of 0.1 m/s, oil supply volume had slight influence on thickness of film in contact area, and the textures exhibited different lubrication performance under different lubrication conditions. At the speed of 0.2 m/s, the oil supply thickness had great influence on film thickness, which increased obviously with the increase of the oil supply thickness. The friction coefficient was the minimum at the oil supply thickness of 200 nm. Provided with hydrodynamic lubrication, surface texture has no friction reduction effect. Provided with boundary lubrication, surface texture has friction reduction effect, and dense texture has relatively smaller friction coefficient. Provided with mixed lubrication, too dense or sparse texture has no friction reduction effect, but properly distributed texture may have friction reduction effect.