An adaptive tunable vibration absorber using magnetorheological elastomers for vibration control of vehicle powertrains
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Powertrains are a crucial subsystem of vehicles and are also a source of the vibration. Because of the wide range of operating frequencies of powertrain, the likelihood of the engine working speed being in the resonance area is very high. Moreover, the resonance cannot be avoided when the engine speed passes through one or more modal powertrain frequencies in the transient stage. An example of the transient stage is that the engine accelerates from idle to top working speeds. Consequently, powertrains may experience a high level of vibration. This thesis presents the development of torsional adaptive tunable vibration absorber (ATVA) using magnetorheological elastomers (MREs) for powertrain vibration control. The effectiveness of the ATVA is examined by both methods: numerical simulations and experimental testing. The MRE is a smart material consisting of a host matrix and magnetic particles and the MRE material is promising for constructing ATVAs because its elastic moduli and damping can be controlled magnetically. Consequently, a MRE-based ATVA can work in a wide frequency range instead of a narrow bandwidth as a traditional vibration absorber does. The principal idea of this thesis is that by tuning the MRE-based ATVA modal frequency and by choosing the ATVA location, powertrain modal frequencies can be actively shifted away from the resonant area for either steady or transient states. Numerical simulations are conducted to show the ATVA’s effectiveness. In addition, the application of multiple ATVAs for dealing with multi-harmonic excitations is numerically examined. The numerical simulations are also used to facilitate the ATVA design, in which, the effect of ATVA parameters such as moment of inertia, stiffness and damping is investigated. A MRE material is fabricated to develop an ATVA for experimental validation. With the MRE measured properties, an ATVA is designed and manufactured. Both designed and experimental results of ATVA modal frequency are in a good agreement. The ATVA can work in a frequency range from 10.75 to 16.5Hz (53% in relative change). To validate the ATVA’s effectiveness, experimental testing is conducted for a powertrain test rig at the University of Technology, Sydney. The powertrain fitted with the ATVA is experimentally investigated. The experimental results show that with the ATVA the powertrain modal frequencies can be shifted far away from the resonant area. This finding confirms that the ATVA works effectively. The torsional MRE-based ATVA is a new device for vehicle powertrain vibration reduction.
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