Comparison of a Hydraulic Engine Mount to a Magnetorheological Engine Mount

A comparison between a hydraulic engine mount and a mixed mode magnetorheological (MR) fluid engine mount is presented. MR fluid is a smart material that changes viscosity in the presence of a magnetic field. In other words, without the presence of a magnetic field, the fluid is classified as a Newtonian fluid, however; with the presence of a magnetic field, the fluid becomes classified as a Bingham plastic. The working modes of the MR mount are squeeze and flow. Hydraulic mounts were developed to address the conflicting requirements of the engine vibration profile. The engine vibration profile can be classified as large displacement in the low frequency range and small displacement in the high frequency range. The hydraulic mount used in this study is an as received OEM mount. The elastomeric top and bottom of the hydraulic mount were used to create the MR mount. In the paper, the advantages and disadvantages of each mount are discussed in detail. Also, a physics based model, coded into the MATLAB/Simulink environment, for the MR mount is presented. The proposed model is derived from the continuity equation and Newtons second law. For the model compressibility of the fluid is not considered, also the rubber is considered to have a singular value for stiffness and damping. The model allows for calculating dynamic stiffness for the mount. Simulation results generated by this model are compared with the experimental results.