Structural Design and Optimization of Nonuniform Chiral Phononic Crystals for Vehicle Interior Noise Reduction

Phononic crystals (PnCs) with nonuniform and chiral design are developed and applied for the reduction of vehicle interior noise. To investigate the effects of structural parameters such as the lattice arrangements and the filling rates, locally resonant PnCs (LRPnCs) are established for calculating sound insulation and bandgap characteristics. Furthermore, the nonuniform LRPnCs with Greek-cross chiral structure are constructed. To improve the sound insulation characteristics of the nonuniform chiral LRPnCs, a genetic algorithm (GA) optimization procedure is performed. Accordingly, the modified nonuniform chiral LRPnCs is designed and simulated to predict the sound insulation characteristics. Experimental verification suggests that the simulated results are in good agreement with the tested ones. The newly designed nonuniform chiral LRPnCs are effective in vehicle interior noise reduction. All the works are expected to be extended to other sound-related fields for noise reductions in engineering.