A Simplified Model to Study EHL Film Collapse During Rapid Halting Motion

Abstract

A theoretical model for describing the EHL film thickness during rapid deceleration is presented. The theory is based on the pioneer work of Ertel (1939) and Grubin (1949), who gave the first analytical solution for the elastohydrodynamic lubrication of a line contact under stationary operating conditions. An extension is made here for rapid halting motion. The proposed model is well adapted when the halting period is small in comparison to the transit time (i.e. 2b/u, ratio between the contact width and the rolling speed). This work completes the model of Glovnea and Spikes (2001b), appropriate for slow halting motion but which suffers from experimental fitting, and the model of Chang (2000) that is more suitable for speed or load oscillations at a wavelength close to the transit time.

This behavior implies that stop-start, reciprocating or rapidly halting machine components may be able to maintain a separating film for longer than would be expected based on steady-state EHL theory. An application to a ball bearing arrangement in a space mechanism is finally made in order to assess the model capabilities.

Presented at the 57th Annual Meeting in Houston, Texas May 19–23, 2002

KEY WORDS:

• Elastohydrodynamic Lubrication
• Rolling Element Bearings
• Engineering Analysis and Computing
• Aerospace Tribology

Notes

Presented at the 57th Annual Meeting in Houston, Texas May 19–23, 2002