Abstract

The instability of oil film stiffness in mixed elastohydrodynamic lubrication (EHL) is a prominent cause of the fretting wear of continuously variable transmission pulley–metal sheet friction pairs. In severe cases, it can induce dynamic system failure. In this study, an oil film normal stiffness model equivalent to a massless spring element is established using linear contact mixed EHL theory. The effects of microscopic parameters (roughness amplitude) and macroscopic operating parameters (torque ratio) on the oil film stiffness in the pulley–sheet contact area are studied. The film stiffness increases initially and then decreases with an increase in roughness amplitude. In addition, it increases continuously and then stabilizes with an increase in torque ratio. The effects of macro- and microparameters are considered and a safety threshold model of oil film stiffness is established. Results show that oil film stiffness exhibits the highest safety stability when the roughness amplitude is 0.10 μm and the torque ratio is 0.8. The influence of roughness amplitude on the safety threshold of oil film stiffness is greater than that of torque ratio.

摘要

混合弹性流体动力润滑（EHL）中油膜刚度的不稳定性是导致无级传动皮带轮-金属板摩擦副微动磨损的主要原因。在严重的情况下，它会导致动态系统故障。在本研究中，利用线性接触混合 EHL 理论建立了等效于无质量弹簧元件的油膜法向刚度模型。研究了微观参数（粗糙度幅度）和宏观操作参数（扭矩比）对滑轮-片材接触区域油膜刚度的影响。薄膜刚度最初增加，然后随着粗糙度幅度的增加而降低。此外，它不断增加，然后随着扭矩比的增加而稳定。考虑了宏观和微观参数的影响，建立了油膜刚度的安全阈值模型。结果表明，当粗糙度幅度为0.10 μm和扭矩比为0.8时，油膜刚度表现出最高的安全稳定性。粗糙度幅度对油膜刚度安全阈值的影响大于扭矩比。