Improved torque roll axis decoupling axiom for a powertrain mounting system in the presence of a compliant base

The existing torque roll axis decoupling theories for powertrain mounting systems assume a rigid foundation, thus ignoring dynamic interactions between the powertrain and other sub-systems. To overcome this deficiency, a coupled mounting system problem is formulated based on the linear time-invariant system theory. The influence of a compliant base on torque roll axis decoupling is first analytically examined in terms of eigensolutions and frequency responses. Then, a new analytical axiom is proposed based on decoupling indices as well as given the properties of the coupling matrix. Five examples are chosen to examine frequency and time domain responses given the torque excitation along the crankshaft axis. To satisfy the new condition, the mounting system is redesigned in terms of the stiffness rates, mount locations, and orientation angles. The results show that the torque roll axis of the redesigned powertrain mounting system is indeed decoupled in the presence of a compliant base (given oscillating or impulsive torque excitation). Finally, eigensolutions are validated by using published data.