For the problem of automobile interior noise caused by driveline torsional resonance

a new idea of controlling the interior noise by installing a multi-degree of freedom (multi-DOF) torsional vibration absorber was proposed and experimented. The experimental results show that the interior noise is reduced by more than 5 dB when a multi-DOF torsional vibration absorber is installed

indicating that this measure for reducing the interior noise is effective. The universal dynamic magnification factor expressions of the multi-DOF torsional absorber with any degree of freedom were derived. The parameters of the absorber in parallel or series with the degree of freedom from one to ten were optimized and compared using the SQP method based on the derived expressions. The analysis shows that a better damping effect can be obtained by increasing the degree of freedom under the conditions that the sum of the ratios of inertias is kept same and the degree of freedom is less than three. This provides a theoretical basis for the choosing of the degree of freedom for such absorber in practice.