Influence of propeller shaft bending vibration on drivetrain gear dynamics

A new multi-coordinate dynamic model of a hypoid geared rotor system considering the propeller shaft bending effect is formulated. The bending flexibility of propeller shaft is modeled as a lumped parameter set applying the component mode synthesis. The pinion and gear are modeled as flexibly coupled rigid bodies with backlash nonlinearity and time-varying mesh coupling. The kinematic transmission error is assumed to be the main excitation. The solution is obtained by employing the explicit Runge-Kutta integration method with adaptive time step, which yields the dynamic mesh force and also the vibratory response of the gear bodies in time domain. The frequency response functions are then determined by computing the root-mean-square of the time domain solutions at each frequency point. The analyses show that the effect of propeller shaft bending flexibility and damping on the geared rotor system dynamics are found to be mode shape dependent. It is further observed that increasing the damping of propeller shaft can effectively reduce the dynamic mesh force. This indicates that the damping treatment on propeller shaft can be a potential application to reduce the gearbox vibration and noise response.