This paper presents a conceptual adaptive tunable vibration absorber (ATVA) with soft magnetorheological elastomers (MREs) for vibration reduction of vehicle powertrain systems. The MRE material used in this application has a rubbery silicone polymer matrix and ferrous fillers in fraction of 27.6% by volume. For such a soft MRE the elastic modulus significantly increases due to the MR effect. Thus, the ATVA can work effectively in a wide frequency range (the increase in frequency more than 10 times) instead of a narrow bandwidth as a conventional dynamic absorber does. Numerical simulations of a powertrain fitted with the ATVA are used to validate its effectiveness. The obtained results show that the powertrain vibration can be significantly suppressed. This novel ATVA will be applicable to the vibration reduction of powertrains.

During the transient stage of acceleration, the powertrain experiences a period of high level vibration because the engine speed passes through one or several powertrain natural frequencies. This paper presents a concept design of an adaptive tuned vibration absorber (ATVA) using a new magnetorheological elastomer (MRE) for powertrain transient vibration reduction. The MRE material used to develop the ATVA is a new one, which is synthesized from a highly elastic polymer and carbonyl iron particles of 3-5 and 40-50 μm. Under a magnetic field of 0.3 T, the MRE material has a giant increase, which is more than two orders, in both the storage and loss moduli. To facilitate the ATVA design, effective formulae for the storage modulus and loss factor were derived as explicit functions of the applied magnetic field density. With the derived formulae, ATVA parameters such as the stiffness and damping coefficients were converted effectively from the magnetic field density. Thus, the ATVA frequency can be tuned properly according to the excitation frequency. Numerical simulations of a powertrain system fitted with the ATVA were conducted to examine the ATVA proposed design. By using the MRE-based ATVA, the powertrain natural frequencies can be actively tuned far away from the resonant area of excitation frequency. Also, the time histories of powertrain frequencies depending on the magnetic field density before and after installing the ATVA have been compared to show that the resonant phenomena have been dealt with completely. As a result, the powertrain transient vibration response is significantly suppressed. In addition, the effect of the ATVA's moment of inertia, stiffness and damping on the ATVA's effectiveness during the transient stage was investigated to choose the ATVA's optimal parameters. The MRE-based ATVA will be a novel device for powertrain vibration control not only for the steady stage but also for transient vibration.

This article presents the development of a torsional adaptive tunable vibration absorber using a magnetorheological elastomer for vibration reduction of a powertrain test rig. The magnetorheological elastomer used to develop the adaptive tunable vibration absorber consists of silicone polymer, silicone oil and magnetic particles with the weight percentages of 60%, 20% and 20%, respectively. Experimental testing is conducted to obtain the magnetorheological elastomer's properties, such as Young's modulus and the damping ratio, and effective formulas are derived to facilitate the design of the adaptive tunable vibration absorber. With the derived formulas, a magnetorheological elastomer-based adaptive tunable vibration absorber is designed and manufactured, and experimental testing is also conducted to validate the design. The results of experiments show that the magnetorheological elastomer-based adaptive tunable vibration absorber can work in a frequency range from 10.75 to 16.5 Hz (53% relative change). Both the designed and experimental results of the adaptive tunable vibration absorber's frequencies are in good agreement. A powertrain model is used to validate the magnetorheological elastomer-based adaptive tunable vibration absorber's effectiveness, and the numerical simulations show that the powertrain frequencies are shifted away from the resonant frequency; thus, the powertrain's steady-state vibration can be significantly reduced. This magnetorheological elastomer-based adaptive tunable vibration absorber will be a promising new device for vibration reduction of vehicle powertrains.