Comparison of 1- and 2-DOF model of Engine Mount with MR Damping

Vibration attenuation and force transmission of an MR engine mount were investigated. Two different models, the conventional 1-DOF and more sophisticated 2-DOF containing vehicle chassis dynamics, were compared in theoretical analysis. The engine's displacement response and transmitted force to the vehicle body were derived and used as performance indicators. Theoretical results inferred that displacement response would be overestimated but the transmitted force be underestimated in the simplest 1-DOF model. The differences could be up to 40% (displacement) and 20% (force) depending on engine mount's damping ratio. A flow mode MR damper was then designed and fabricated. Experiments verified MR's performance and the results showed satisfactory agreement with the theoretical calculations. This investigation enhanced the capability of MR damper implemented into engine mount for vibration and force reduction at low speeds. It also showed to the audience that in vehicle dynamics the chassis dynamics might need to be included in designing the engine mount.