关于椭圆接触弹流润滑Hamrock-Dowson膜厚公式的再思考

Reconsideration of Hamrock-Dowson Formula for Elliptic Contact Elastohydrodynamic Lubrication

使用常用的Hamrock-Dowson公式计算椭圆点接触中心油膜厚度时发现:当维持接触区中心赫兹压力为常数,增加椭圆比ke超过一定值时,得到的中心膜厚不升反降,这与其物理本质相悖.应用有限单元法重新对等温椭圆接触弹流润滑问题进行了数值计算,提出新的表征椭圆接触的综合几何参数.在较大的速度和载荷范围内下,依据数值计算结果,拟合出修正端泄因子和修正中心膜厚公式.修正公式与数值计算结果相吻合,且正确地表达了膜厚与椭圆比的关系.

Hamrock-Dowson formula is commonly used to calculate the central film thickness of elliptical contact EHL.It is found that when the Hertz pressure at the contact center is maintained as a constant and the ellipticity ratio ke is larger than a critical value,the central film thickness obtained would decrease instead of rise,which is contrary to its physical essence.Numerical calculation on isothermal elliptic contact elastohydrodynamic lubrication was carried out using finite element method and a new comprehensive geometric parameter was proposed to characterize the elliptic contact.Based on the numerical results,a modified side leakage factor and a modified central film thickness formula were obtained under a large range of speeds and loads.The modified formula was in agreement with the numerical results,and the relation between film thickness and elliptic ratio was given correctly.