Dynamic Analysis of Sliding Friction in Rotorcraft Geared Systems
Final progress rept. 1 Aug 2002-31 Jul 2005
OHIO STATE UNIV RESEARCH FOUNDATION COLUMBUS
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This comprehensive study has examined the key effects of sliding friction in spur and helical gear dynamic models, vibro-acoustic sources and geared system responses. First, many dynamic phenomena that emerge due to the interactions between time-varying mesh stiffness, sliding friction andor surface finish are successfully formulated. Second, new multi-degree-of-freedom models considering both torsional and translational dynamics of spur and helical gear pairs have been developed. These include time-varying mesh stiffness, sliding friction excitation and shaftbearing compliances. Line-of-action and off-line-of-action motion predictions, based on the lumped gear dynamic models, match well with a benchmark finite elementcontact mechanics code. Third, new mathematical models have been proposed to examine structure-borne and air-borne noise that should arise due to surface asperities as a function of operating speed and surface finish. Fourth, mobility type frequency response studies of the system vibro-acoustic characteristics provide new insights into dynamic forces at the bearings and sound radiation. Fifth, two sets of experimental studies at ARLNASA Glenn were conducted. Gear noise source and lumped system models match well with experiments on ARLNASA spur gears. Finally, a set of helical gears has been designed that clearly isolate the effects of sliding friction. Suggestions for future research are included.