Study on vibration isolation performance and control method of magneto-rheological mounts

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Study on vibration isolation performance and control method of magneto-rheological mounts


Author: Yang, Qing
Title: Study on vibration isolation performance and control method of magneto-rheological mounts
Degree: M.Sc.
Year: 2014
Subject: Motor vehicles -- Vibration.
Hong Kong Polytechnic University -- Dissertations
Department: Faculty of Engineering
Pages: xxiv, 152 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record:
Abstract: As a result of the improvement of automotive industry, hybrid technologies are applied to modern vehicles in order to reduce fuel consumption and emissions. The hybrid vehicles which are equipped with distinct power sources have higher efficiency than that of vehicles with conventional internal combustion engines. The advantages of hybrid technologies, however, tend to lead to challenging problem of noise, vibration and harshness (NVH). The NVH problem existed in hybrid vehicles is mainly caused by the switching among the multiple power sources and the vibration and shock associated with them occur over a wide range of frequencies. The passive vibration isolators such as elastomeric and hydraulic mounts are unable to totally solve this problem. Although active mounts are effective to mitigate and isolate such shocks and vibrations, they require high power consumption and may cause instability problems. It has been proven that semi-active vibration isolators are as effective as active mounts while being less expensive and complex. The application of a mount incorporated magnetorheological (MR) fluid has gained significant development in vibration isolation. The MR mounts could offer an outstanding capability in semi-active vibration isolation for various applications due to excellent dynamical features such as large force capacity, fast response, and lower power consumption. In this thesis, combination of MR mount with some novel design features in hydraulic mounts is studied to develop a novel vibration isolator which is effective over a wide range of frequencies. This research began with a comprehensive review of passive and semi-active mounts. Following this, an introduction of MR mount including its structures and working principles was presented. In addition, some guidelines in designing a MR mount such as structure design of rubber top and MR valve were given. Furthermore, the mathematical models of three MR mounts with different novel features were developed based on bond graph method. The analytical models were simulated and numerically solved by MATLAB software. The dynamic characteristics and vibration isolation performances of the mounts were predicted by the simulation results. The parametric studies on dynamic properties and transmissibility of the mount were conducted to evaluate the effect of design parameters on mount performance. Finally, in order to control the transmitted force from engine to chassis, a vibration isolation system incorporating MR mount with a fuzzy controller was constructed in MATLAB/Simulink based on the two degree of freedom (DOF) quarter car model. The simulation results were used to show the vibration isolation performance of MR mount system.

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