Design and modeling of a mixed mode magnetorheological (MR) fluid mount

Noise and vibration have always affected not only the operation of various devices but also people's comfort. These issues are highly present in currently emerging technologies like hydraulic launch assist vehicles. While the switching mechanisms in hydraulic hybrid vehicles enhance fuel efficiency, they cause complicated patterns of noise and vibration. This, combined with a wider range of frequencies excited by this mechanism requires advanced vibration isolators that can provide variable damping and stiffness. A solution to this problem can be provided by MR fluid based mounts. An MR fluid mount is capable of changing its stiffness and damping characteristics to accommodate various input excitation amplitudes and frequencies. This paper presents simulated results for a mixed mode magnetorheological (MR) fluid mount. If the MR mount is only working in one mode, either flow or squeeze mode, the range of isolation force provided by the damping and spring rate of the mount is constrained by the geometry of the respective mode. However, when the mount operates in both modes simultaneously, their effects are combined to accommodate a wider range of amplitudes and frequencies of excitation. The mathematical governing equations of the mount are derived to account for its operation with mixed flow modes. These equations implemented in MATLAB/Simulink