Magneto-rheological rubber to reduce noise: reality or fiction? — an experimental inquiry into its effectiveness

The structure-borne sound properties of an isotropic magneto-rheological rubber are experimentally examined in a specially designed test rig within the audible frequency range while applying an external magnetic field. The manufacturer convenient rubber material under the study focus consists of dispersed irregular, micro-meter sized iron particles in a nitrile matrix. The shear modulus is found to depend strongly on both frequency and magnetic field, while the loss factor is almost independent of those factors. Magneto-rheological rubbers applied to vibration isolators promise to have more functionality than conventional rubber isolators while actively, rapidly, continuously and reversibly change rigid body and dynamic stiffness peak frequencies, thereby effectively increasing the isolation also within the audible frequency domain.