The Center for Integrated Manufacturing Studies (CIMS) is studying the improvement of military Light Armored Vehicles (LAVs) for the United States Department of Defense. A focus of this study is the Marine Corps LAVs that are experiencing failures in the planetary assembly which serves as the vehicle's final drive system. The primary failure source is the bushings that provide the interface between the planet gears and their respective pins.
Currently, to detect a bushing failure, vehicle occupants must exit the LAV and place their hand on the wheel hub cover to check for excessive heat. If the hub "feels too hot," travel must stop so the planetary assembly can cool down. These overheating wheel hubs can lead to catastrophic failure of the planetary assembly. Therefore, CIMS is working to analyze these bushing failures and develop a method that will allow occupants to detect potential bushing failures from inside the moving vehicle.
In the past, the relationship of pin-bushing interface temperature and wear showed that temperature does not indicate bushing failure soon enough for practical implementation. It was the intention of this current wear study to evaluate bushing failures using vibration signatures as part of an effort to develop failure prognostic tools for (future) in-service use.
This thesis was conducted as a feasibility assessment study to evaluate bushing failure from a vibration and signal processing standpoint. Accelero meters were used to collect vibration data from the bushings. Collected vibration signatures were analyzed and examined as bushing wear progressed to determine whether or not remaining bushing life could be predicted using vibration signatures.
Vibration data was analyzed from an energy standpoint; that is, the band power was calculated for several frequency bands of interest. Band power was plotted versus bushing wear to reveal any potential relationship between the two. Test results showed that a direct, linear relationship exists between bushing wear and band power in the 2000 to 2100 Hz frequency range.
The results of this thesis suggest that vibration data can be used to identify the severity bushing wear. Since this investigation was conducted as a feasibility assessment, additional work is required before this wear detection method can be implemented on an actual LAV. It is recommended that similar bushing wear-vibration studies be conducted where bushings are tested on the Mustang dynamometer (at CIMS) and then on an actual LAV.
Library of Congress Subject Headings
Amrored vehicles, Military--Vibration--Prevention; Armored vehicles, Military--Materials--Dynamic testing
Mechanical Engineering (MS)
Department, Program, or Center
Mechanical Engineering (KGCOE)
Mark H. Kempski
Kevin B. Kochersberger
Parnell, Victoria L., "Health Monitoring of LAV Planet Gear Bushings using Signature Analysis Techniques" (2006). Thesis. Rochester Institute of Technology. Accessed from
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