Feasibility Investigation of Zero-Torsional-Stiffness Couplings for Suppression of Resonance and Instability in Helicopter Drive Trains
FLORIDA UNIV GAINESVILLE DEPT OF MECHANICAL ENGINEERING
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An investigation is made of the feasibility of designing a nonlinear shaft coupling, with zero or very low torsional stiffness at predetermined operating conditions, for helicopter drive trains. The purpose of such a coupling is to isolate torsional vibration and eliminate resonances. It is found that a coupling can be designed to have zero torsional stiffness at high rotational speeds by using the centrifugal force field on connecting links from the driving to the driven flange of the coupling. Previous designs of such couplings for low-speed applications have been used successfully in marine diesel drives. Design equations for two types of zero-stiffness couplings suitable for high speed turboshaft-powered helicopters are developed.