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On the Correlation of Specific Film Thickness and Gear Pitting LifeThe effect of the lubrication regime on gear performance has been recognized, qualitatively, for decades. Often the lubrication regime is characterized by the specific film thickness defined as the ratio of lubricant film thickness to the composite surface roughness. It can be difficult to combine results of studies to create a cohesive and comprehensive dataset. In this work gear surface fatigue lives for a wide range of specific film values were studied using tests done with common rigs, speeds, lubricant temperatures, and test procedures. This study includes previously reported data, results of an additional 50 tests, and detailed information from lab notes and tested gears. The dataset comprised 258 tests covering specific film values [0.47 to 5.2]. The experimentally determined surface fatigue lives, quantified as 10-percent life estimates, ranged from 8.7 to 86.8 million cycles. The trend is one of increasing life for increasing specific film. The trend is nonlinear. The observed trends were found to be in good agreement with data and recommended practice for gears and bearings. The results obtained will perhaps allow for the specific film parameter to be used with more confidence and precision to assess gear surface fatigue for purpose of design, rating, and technology development.
Document ID
Document Type
Conference Paper
Krantz, Timothy Lewis (NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
January 22, 2015
Publication Date
October 12, 2014
Subject Category
Mechanical Engineering
Report/Patent Number
Meeting Information
AGMA Fall Technical Meeting 2014(Arlington, VA)
Funding Number(s)
WBS: WBS 380046.
Distribution Limits
Work of the US Gov. Public Use Permitted.
surface roughness

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