Characteristics Analysis And Decoupling Study Of Powertrain Mounting System In The Presence Of A Compliant Base

Engine vibration is one of the main sources of vehicle vibration which affecting vehicle’scomfort and NVH（Noise, Vibration and Harshness）performance. A rational design of a powertrainmounting system can significantly isolate vibration from being transmitted to the vehicle body，increase a vehicle comfort and extend the durability and lifespan of the engine and other vehiclecomponents. Combing with current research achievements and existing problems of the powertrainmounting system, this paper studies the torque roll axis (TRA) decoupling of the powertrainmounting system with different type of the mounts in the presence of a compliant base. The primarywork includes the following aspects.(1) The coupling between the powertrain mounting system and the compliant base has beenanalysed. According to the force and a position matrix respect to the powertrain/compliant basesystem, the uncoupled and coupled model of the powertrain and compliant base system have beenestablished. The eigensolutions of the coupled and uncoupled system are validated by usingpublished data.(2) Based on mode characteristics as well as the TRA decoupling axiom, a new analyticalaxiom of the powertrain rubber mounting system with proportional and non-proportional damping isproposed. The results show that the torque roll axis of the redesigned powertrain mounting systemwith proportional and non-proportional damping is indeed decoupled in the presence of a compliantbase (given oscillating or impulsive torque excitation).(3) Existing motion decoupling studies for a powertrain isolation system assume that the mountstiffness and viscous damping properties are spectrally invariant. To overcome this deficiency, a newanalytical formulation is proposed that incorporates spectrally-varying stiffness and dampingproperties of multi-dimensional mounts in the presence of a compliant base (with many vibrationmodes over the applicable lower frequency regime). A new analytical axiom for the torque roll axis(TRA) decoupling of powertrain motions is also formulated using spectral decoupling indices.Simulation and experiment results demonstrate that the torque roll axis of the redesigned powertrainmounting system is indeed decoupled from other powertrain motions.(4) The problem with spectrally-varying mount properties requires a new analytical framework,especially for eigensolutions. To overcome this void in the literature, a new method has beenproposed by using the properties of the coupling matrix under certain conditions. The simulatedresults show that the new method is effective.(5) A new quasi-linear model of the active mount and the analytical combination model of thepowertrain mounting system have been established. The frequency responses, mode properties and the mount parameters sensitivity analysis of the powertrain mounting system in the presence ofactive mounts have been investigated. Considering the uncertainty of the design parameters in thepowertrain mounting system, the robust model of the powertrain mounting system is established byusing the Monte Carlo analysis and interval analysis. The parameters are optimized by usingnondominated sorting genetic algorithm II (NSGA-II). The simulated results based on the optimumsolutions indicate that the decoupling method we adopt is effective.