Isothermal Elastohydrodynamic Lubrication of Point Contacts: Part IV—Starvation Results

TLDR

The study investigates how lubricant starvation affects minimum film thickness using the authors’ prior theory and numerical method. Lubricant starvation was simulated by moving the inlet boundary nearer the contact center, and contour plots of pressure and film thickness were generated for both fully flooded and starved cases. Results show that the transition between fully flooded and starved regimes occurs at m*≈1+3.06Rxb²Hc,F^0.58 (or 1+3.34Rxb²Hmin,F^0.56), that starved central and minimum film thicknesses can be expressed as Hc,S=Hc,Fm−1m*−10.29 and Hmin,S=Hmin,Fm−1m*−10.25, and that increasing starvation suppresses the pressure spike and markedly reduces film thickness.

Abstract

Utilizing the theory and numerical procedure developed by the authors in an earlier publication the influence of lubricant starvation on minimum film thickness was investigated. This study of lubricant starvation was performed simply by moving the inlet boundary closer to the contact center. From the results it was found that for the range of conditions considered the value of dimensionless inlet distance at the boundary between fully flooded and starved conditions (m*) can be expressed simply as m*=1+3.06Rxb2Hc,F0.58 or m*=1+3.34Rxb2Hmin,F0.56 that is, for a dimensionless inlet distance (m) less than m*, starvation occurs, and for m ≥ m*, a fully flooded condition exists. Furthermore, it has been possible to express the central and minimum film thickness for a starved condition as Hc,S=Hc,Fm−1m*−10.29Hmin,S=Hmin,Fm−1m*−10.25 Contour plots of the pressure and film thickness in and around the contact are shown for the fully flooded and starved lubricant condition. From these contour plots it was observed that the pressure spike becomes suppressed and the film thickness decreases substantially as starvation increases.