磁気応答性材料を用いた振動制御装置による車内振動/騒音を低減する試み

抄録

In this study, a broad-band frequency tunable dynamic vibration absorber was designed and fabricated based on the primary design principle of a mass damper. A magneto-rheological elastomer (MRE) 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. A coil to generate the magnetic field was also used as a movable mass to decrease the total weight and to create a constant closed loop of the magnetic force. Results of preliminary performed experiments show that the vibration of an acrylic flat plate could be reduced automatically in the frequency range from 50 to 150 Hz with simple techniques to determine the strength of the magnetic field to be applied to the MRE by controlling the electric current applied to the coil. Then, we applied the proposed absorber to decrease the noise in a vehicle cabin by absorbing the vibrational acceleration of the vibrating parts of the vehicle. We could reduce interior engine booming noise or road noise according to the small steps by absorbing the vibration of the vibrating parts of the vehicle with controlling the electric current applied to the coil based on its engine speed or vehicle speed.