平行运动的粗糙表面润滑承载性能研究

Load Carrying Capacity of Parallel Movement Lubricated Rough Surfaces

分析了微米级润滑膜条件下，光滑表面在静止粗糙表面上平行运动时的润滑状态及其承载机制，利用Reynolds流体润滑方程分析粗糙度对油膜压力、载荷及摩擦系数的影响，采用有限差分法计算在正弦和随机粗糙峰条件下油膜的压力分布曲面图，通过改变正弦粗糙度的峰高和波长分析油膜承载能力和摩擦系数随粗糙度变化的规律，同时分析了最小油膜厚度对润滑状态的影响．结果表明：两光滑平行运动的平面无法承载，而粗糙表面微粗糙峰的收敛楔形部分可以形成流体动压润滑膜并承受一定载荷；在给定最小油膜厚度的条件下，随着正弦波峰值增加，承载能力达到最大值后缓慢降低，摩擦系数达到最小值后缓慢增大；除了粗糙峰波长很小时摩擦系数很大以外，波长对摩擦系数的影响很小，而承载能力随波长以二次曲线变化并出现最大值；在给定粗糙度幅值条件下，当最小膜厚在1～100μm时，随着最小油膜厚度的增加，承载能力减小，摩擦系数逐渐增大．

Load carrying mechanism and lubrication state of one smooth plate against one rough stationary plate with parallel motion were numerically analyzed at micro scale. Reynolds equation was used to analyze the influence of roughness on the parameters such as pressure distribution, load carrying capacity, friction coefficient and etc. Pressure distribution maps of sine roughness and random roughness were plotted according to the analysis results by finite difference method. Load carrying capacity and friction coefficient as function of peak height and wavelength of roughness were discussed in detail, and the influence of film thickness on lubrication states was also analyzed. The results indicate that there was no way to bear load with two smooth parallel movement surfaces, while the convergent wedge of tiny rough peak on rough surface could create positive hydrodynamic lubrication film and support an outside load. Under a fixed lubrication film thickness, the load carrying capacity reached maximum value and then reduced slowly with increasment of rough peak height, while friction coefficient quickly droped to minimum value and then slowly rose. Furthermore, if the rough peak height was fixed, and the minimum film thickness was between 1 to 100 μm, the load carrying capacity kept dropping gradually with increasment of minimum film thickness, but friction coefficient rose continuously.