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A primary concern in the design of serpentine belt drive systems is resonant strand vibrations induced from engine excitation. Two analysis approaches to investigate the system vibrational response have been reported in the literature. The first, denoted as the “decoupled analysis” approach, employs longitudinal belt stiffness and takes into account only pulley rotation and tensioner displacement as system degrees of freedom. Transverse belt vibration (normal to belt travel) on all belt strands is decoupled from the analysis. The second, denoted as the “coupled analysis” approach, combines transverse tensioner strand belt motion with pulley rotation and tensioner displacement. Transverse belt vibration on strands between fixed pulleys remains decoupled from the system. This paper provides apparently the first cross comparison of these two analysis techniques on three distinct serpentine belt system configurations reported in the literature.

This paper illustrates the potential benefits of identifying planet gear bushing failures in military Light Armored Vehicles (LAVs) using vibration signature analysis techniques over conventional thermocouple methods. A pneumatically driven test rig was developed to measure the vibrational response of a lubricated dimpled bushing using accelerometers mounted externally to the bushing housing. Fourier-based signature analysis techniques are employed to track the wear history of the bushing liner material under steady load and steady shaft rotational speed. Vibration data collected from the accelerometers was analyzed by calculating the band power of specific frequency bands. Three separate run-to-failure tests showed a direct linear relationship between band power and bushing wear for frequency bands that may be related to the worn dimpled pattern of the bushing. The data was also shown to be a reasonable predictor of bushing wear within specified confidence bounds.