Study on bandgap of a novel phononic crystal with low-frequency sound insulation

Abstract

To solve the problem of low-frequency noise in the environment, a two-dimensional Helmholtz-type phononic crystal with a labyrinth tube was designed in the paper. First, the low-frequency band structure was calculated by the finite element method (FEM) and transfer matrix method (TMM). Second, the bandgap formation was analyzed by using an acoustic pressure field, and the “spring-oscillator” equivalent model of the structure was established. Finally, the influences of structural parameters on the first bandgap were investigated. Results show that there are four bandgaps in the frequency range of 0–300 Hz, and the lower limit of the first bandgap can be as low as 12.15 Hz, which improves the low-frequency sound insulation ability of phononic crystals of the same size. The calculation results of the two methods (FEM and TMM) are basically consistent. Research on the influencing factors of the bandgap shows that the increase in the length of the tube will reduce the upper and lower limits of the bandgap and narrow the bandgap width. With the increase of the lattice constant, the upper limit of the bandgap decreases, while the lower limit of the bandgap remains unchanged. The design provides a new method to solve the problem of low-frequency noise reduction.

A Many-Objective Joint Parallel Simulation Method for Acoustic Optimization Design of Sound-Absorbing Structures

“…Subpopulations are then subjected to constraint determination and ideal point finding operations. (7) The parent and child populations are merged, and sequential operations, including non-dominated sorting, target space normalization, a calculation of reference lines, an association of individuals with reference points, and a selection of dominant populations are carried out. (8) If the termination condition is met, the optimal Pareto solution is output; otherwise, steps ( 5) through ( 8) are repeated.…”

“…Using parameters, such as the total stiffness and damping, as independent variables, and the average sound absorption coefficient in a specific frequency band as the optimization objective, Li et al [6] have created a type of loudspeaker with a good sound absorption performance. Han et al [7] have constructed a labyrinthine Helmholtz phonon crystal and have concluded that increasing the tube length and preserving a small lattice constant could significantly enhance the structure's low-frequency sound insulation capacity. Chen et al [8] have constructed a resonant metamaterial plate with a front radial film and have concluded that increasing the plate thickness and decreasing the film thickness could effectively improve the broadband and low-frequency properties.…”