: Hydraulic engine mounts are generally applied to the aerospace and automotive applications for the purpose of cabin noise and vibration reduction. Here in this thesis, a new hydraulic engine mount design is proposed that uses two working fluids. This new design has two notch frequencies and two peak frequencies. Under special conditions, it is shown that the peak frequency can be eliminated. As a result, one can obtain a hydraulic engine mount design with only one notch frequency but no peak frequency. This can be achieved by using a controllable fluid or a high viscosity fluid as one of the working fluids. Such hydraulic engine mounts (passive and semi-active) utilize magneto-rheological fluid as their working fluid. Next, the mathematical models and some discussions on the simulation results are presented. In another part of the thesis, a new hydraulic engine mount with a controllable inertia track profile is proposed and its dynamic behavior is investigated. An active hydraulic engine mount consists of a conventional passive fluid mount, an electromagnetic actuator (voice coil) and a capacitive circuit is proposed for automotive applications. Finally, a magneto-rheological hydraulic engine mount is fabricated and tested. Some discussions on the results are also presented. Key Words Hydraulic Engine mount, Semi-active and active mount, Magneto-rheological fluid, Elimination of peak frequency
