Design and Application of a Lightweight Plate-Type Acoustic Metamaterial for Vehicle Interior Low-Frequency Noise Reduction

To reduce the low-frequency noise inside automobiles, a lightweight plate-type locally resonant acoustic metamaterial (LRAM) is proposed. The design method for the low-frequency bending wave bandgap of the LRAM panel was derived. Prototype LRAM panels were fabricated and tested, and the effectiveness of the bandgap design was verified by measuring the vibration transmission characteristics of the steel panels with the installed LRAM. Based on the bandgap design method, the influence of geometric and material parameters on the bandgap of the LRAM panel was investigated. The LRAM panel was installed on the inner side of the tailgate of a traditional SUV, which effectively reduced the low-frequency noise (around 34 Hz) during acceleration and constant-speed driving, improving the subjective perception of the low-frequency noise from “very unsatisfactory” to “basically satisfactory”. Furthermore, the noise reduction performance of the LRAM panel was compared with that of traditional damping panels. It was found that, with a similar installation area and lighter weight than the traditional damping panels, the LRAM panel still achieved significantly better low-frequency noise reduction, exhibiting the advantages of lightweight, superior low-frequency performance, designable bandgap and shape, and high environmental reliability, which suggests its great potential for low-frequency noise reduction in vehicles.