 Recently, studies on broadband vibration noise control technology have been actively conducted. Along with the increased use of mechanical products and an increase in speed and operation modes, the frequency of vibration noise generated has become broadband as compared with the conventional products. In addition, with the developments in the automobile industry with regard to electric vehicles and automated cars, the demand for weight and noise reduction in vehicles is increasing. Therefore, there is a demand for a technology which is capable of controlling the vibration noise of frequencies that are higher and more broadband than the past frequencies. For this reason, active vibration and noise control technology, which has been applied to many mechanical products and has contributed to the improvement of vibration noise performance, has recently attracted considerable attention. While various broadband vibration control techniques have been studied, most of the developed devices are either heavy or exhibit significant power consumption, and the actuator and the variable characteristic materials used in the device are expensive. Against this background, we designed and fabricated a broadband frequency-tunable dynamic absorber that reduces cost, weight, and power consumption. The design of the proposed absorber was based on the principle of the dynamic vibration absorber. A magneto-rheological elastomer that can change the relative stiffness when an external magnetic field is applied was used to control the natural frequency of the movable mass of the absorber. One of the distinctive features of this study is that a coil to generate the magnetic field was also used as a movable mass.

 We first applied the dynamic absorber to reduce the noise and vibration in a cabin of the vehicle, which is caused by the input force from the road surface while the vehicle is moving.

 We performed four different experiments. First, we performed experiments to determine a suitable position for the dynamic absorber by the simultaneous measurements of the vibration near the wheel and the noise and vibration in the cabin. Noises audible to the driver and the vibration of the seat and steering were measured. Second, we designed and fabricated the dynamic absorber to obtain the best vibration absorbing effect. Based on the results of the experiments described above, we determined the required characteristics of the absorber, namely, the natural frequencies and the damping ratio. Then, we fabricated the MRE to realize the required characteristics of the absorber. Third, we confirmed the characteristics of the absorber using hammer impact tests. We measured the natural frequency and the damping ratio of the absorber under various conditions when electric current was applied to the coil of the absorber. Finally, we set the absorber on the subframe of the vehicle near its wheel to reduce the noise and vibration in the cabin. We ran the vehicle with the absorber on smooth and rough roads at a speed of 10, 20, and 30 km/h. The vibrational acceleration and noise in the cabin were measured and the reduction effect by the absorber was measured.

 Experimental results showed that the vibrational acceleration of the subframe near the wheel had a high correlation with the noise and vibration in the cabin. Therefore, it was found that this position was the most suitable to place the dynamic absorber. The hammer impact test results show that the present absorber could change its natural frequency from low to high to reduce the vibration at the subframe as intended by changing the receipt to make the MRE function properly. It was found that it could reduce the road noise in a vehicle cabin to approximately 2.5 dB at the maximum by reducing the vibrational acceleration of the subframe at a vehicle speed of 10 to 30 km/h. Furthermore, the measurement results of the noise in a vehicle cabin with the absorber also showed that the 2nd-order engine booming noise could be reduced by approximately 4 dB at the maximum as an additional benefit.


On the Semi-Active Noise and Vibration Control in a Vehicle Cabin Using Magneto-Rheological Elastomer Based Dynamic Vibration Absorber

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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