The Effects of Externally Magnetic Fields and Electrically Conducting Lubricants at Transient Squeeze MEHL Motion with Elastic Coating

導電潤滑劑及外部磁場之複合效應對具彈性鍍層接觸表面之暫態擠壓磁彈液動潤滑研究

朱力民(Li-Ming Chu) ； 張育斌(Yuh-Ping Chang) ； 張簡才萬(Chang-Jian, Cai-Wan)

《中國機械工程學刊》 43卷1期 (2022/02) Pp. 29-35

摘要

The pure squeeze magneto-elastohydrodynamic lubrication (MEHL) motion of point contacts with an electrically conducting fluid in transverse magnetic field on elastic coating is explored under constant load process. The modified Reynolds, the rheology, the force balance, and the elastic deformation equations must be solved simultaneously to obtain the transient pressure profiles, film shapes, elastic deformation, and normal squeeze velocities. The differences between classical EHL and MEHL are discussed during the pure squeeze process. The simulation results reveal that the effect of externally applied magnetic field is equivalent to enhancing the effective lubricant viscosity. Therefore, as the Hartmann number (M) increases, the effect becomes more obvious. The larger the Hartmann number, the thicker the central film thickness and minimum film thickness, the smaller the maximum central pressure, the later the maximum central pressure and the dimple are formed, the smaller the central normal squeeze velocity. The central pressure decreases with increasing M at the initial stage. The central pressure increases with increasing M at the deformation stage.

關鍵字

MEHL ； external magnetic field ； squeeze ； elastic coating ； electrical conducting

並列摘要

本研究探討彈性鋼球與彈性鍍層表面間在外加磁場作用及電導流體潤滑下的純擠壓磁彈液動定負荷下之擠壓的特性。將暫態修正雷諾方程式、流變方程式、力平衡方程式及彈性變形方程式耦合起來，求解此一非線性微分方程組，可解得暫態的壓力分佈、油膜分分佈、彈性變形與擠壓速度。並討論在純擠壓過程中傳統彈液動潤滑和磁彈液動潤滑之間的差異。其結果顯示，增加外部磁場於導電型潤滑劑相當於提升潤滑劑的有效黏性，因此當哈特曼數（M）增加時，提昇的效果會更為明顯。哈特曼數越大，中心膜厚和最小膜厚越厚，最大中心壓力越小，最大中心壓力和內凹坑形成越晚，中心法向擠壓速度越小。初始階段中心壓力隨著哈特曼數的增加而減小。變形階段的中心壓力隨著哈特曼數的增加而增加。