A study on the application of locally resonant acoustic metamaterial for reducing a vehicle's engine noise

In automotive development satisfying both low noise and lightweight is challenging since most of the conventional noise and vibration countermeasures such as insulation pad, deadener and reinforcing material have their performance closely related to their mass. This paper proposes a novel noise and vibration insulation pad design based on locally resonant metamaterial to improve the noise and vibration insulation of a vehicle while reducing the weight of the current sound insulation pad. In the first part, a major automotive noise isssue due to the engine noise is introduced, and various resonant metamaterial designs are devised and their noise and vibration insulation performance is experimentally assessed. In the second part, the selected resonant metamaterial designs are applied to a firewall panel in a real car. Their noise insulation performance is again experimentally evaluated. As a result, teh insulation pad with resonant metamaterials is lighter and acoustically outperforms the current insulation pad solution in the frequency region where the resonant metamaterials are effective while having similar acoustic performance outside this frequency region.