In-plane attenuation zone and its optimization of periodic porous plates

The periodic porous plate with Bragg scattering mechanism is difficult to obtain low bound frequency and wide attenuation zones.One type of periodic porous plates with rhombus holes is optimized and designed.Based on the finite element method with periodic boundary conditions,the in-plane dispersion curves of periodic porous plates are calculated via COMSOL.The frequency responses of periodic porous plates are investigated by ANSYS simulation.The periodic porous plates are suspended and dynamically tested under sinusoidal excitations.The results show that periodic porous plate with rhombus holes has wider attenuation zones than those with circular and hexagonal holes.The material properties have a great influence on the attenuation zones.Nitrile-butadiene rubber and silicon rubber are easy to obtain low-frequency attenuation zones.Increasing porosity results in lower and wider attenuation zones.The width of attenuation zone increases as the horizontal angle of rhombus holes increases.The analysis on the generation mechanism of attenuation zones shows that the periodic porous plate has both characteristics of Bragg scattering and local resonant phononic crystals,which indicates the inherent relation between two types of mechanisms.The optimized periodic porous plate has a complete attenuation zone ranging from 5281.76 Hz to 8824.30 Hz.The vibrations are significantly reduced when the number of periods is not less than two.The attenuation range obtained by the numerical method is generally consistent with that of experiment.The research does shed light on the noise insulation plate,and has the potential application in improving sound environment due to the simple manufacture.