Study on the bandgap broadening of two-dimensional acoustic crystals by structure-induced equivalent mass change

• A novel method to tune phononic crystal band gaps by modifying unit cell structure. • Effects of substrate, coating, scatterer sizes on band gaps in 3-component phononic crystals. • Cylindrical-to-cone/hollow scatterer shapes significantly widen band gaps in phononic crystals. • Scatterer structural changes broaden band gaps without material replacement. Research has found that low-frequency broadband phononic crystals can effectively reduce vibration and noise. This paper proposes a method to broaden the bandgap of phononic crystals by adjusting the unit cell structure. Three-component phononic crystal unit cells were designed and optimized based on specific parameters. The study explored the effects of structural changes on the equivalent mass and bandgap characteristics of unilateral three-component and matrix-based five-component symmetrical structures. By transforming cylindrical scatterers into other shapes, the bandgap width was increased. This discovery is beneficial for broadening the bandgap without changing materials, which is advantageous for engineering applications.