Abstract The influence of acoustic radiation is considered in the prediction of noise attenuation effect of sound barrier, which provides a theoretical reference for further improving the insertion loss of sound barrier. Based on the theory of thin plate vibration, the vibration mode and natural frequencies of sound barrier under arbitrary boundary conditions are established by using two-dimensional beam function method, and the forced vibration response of the sound barrier is calculated based on the modal superposition method. MATLAB software (MathWorks Company, Natick, Massachusetts, USA) is used to calculate the natural frequencies and the radiated sound power level of the sound barrier, which indicated that the sound radiation caused by external excitation would significantly increase the sound pressure level at the received point, which should be considered as one of the influencing factors in the prediction of noise attenuation effect. The influence of diverse structural parameters on the radiated acoustic power is compared, providing an excellent reference for the design of sound barrier with low noise.
In this paper, a new hybrid absorption system is posed which is composed of a layer absorbent material and a movable rigid wall. The speed of the movable rigid wall is adjusted in order to make the acoustic impedance of the absorption material match the acoustic impedance of the air, so that the absorption coefficient is maximal. Finally, a numerical calculation and an experiment are carried out, both numerical and experimental results of such a system are presented for a normally incident plane wave. The numerical and experimental results indicate that the absorption effect is effecting at middle and low frequencies and imperfect in high frequencies where passive absorption is dominant.
Abstract The sound isolation of locally resonant phononic crystal panels is significantly affected by geometrical and material parameters. In this paper, the variation of sound insulation is analyzed and observed by designing phononic crystal plates with different geometrical and material parameters. The research results indicate that in the structure of locally resonant phononic crystal plates, the density of scatterers and matrix materials has the most significant impact on sound insulation performance. As the density increases, the maximum sound insulation initially increases and then decreases. The density, elastic modulus, and Poisson’s ratio of the coating layer material also affect the sound insulation performance. Additionally, the filling rate of the scatterer structure influences the performance to some extent. Therefore, when designing locally resonant phononic crystal plates, the material density of scatterers and the matrix should be prioritized, followed by changes in the scatterer structure, and finally, the selection of an appropriate coating material.
A method of active absorption and active isolation using piezoelectric ceramic is posed for the excellent mechanic and electric coupling performance of piezoelectric material. Two pieces of piezoelectric ceramic are used as materials of active absorption and active isolation, two pieces of PVDF are placed in the front of the piezoelectric ceramic at distances d and 2d to measure the incident plane wave and the reflected wave. Voltages are applied on the surface of the piezoelectric ceramic in order to make the reflected wave and transmission wave zero using adaptive controlling. Finally emulation is carried out with plane wave and good absorption and isolation effects are achieved.
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