Steady-state Sponse Of Two-dimensional Ternary Locally Resonant Phononic Crystals

In the present world,noise pollution, air pollution and water pollution are recognized as the three major environmental pollutions. With the urbanization proceeding, noise pollution becoming a more serious problem which disturbing people's lives in hearing, relaxing, communication and psychological physiology. Test result shows that, the phononic crystals display good performance in noise insulation. Phononic crystals are the periodic elastic materials or structures with elastic wave band gaps which has low-frequency band-gap. It has a significant foreground application in acoustic field. The research of phononic crystal starts at 1992, and in current, only a little study on two-dimensional ternary acoustic mechanism of phononic crystals.This paper is based on previous studies, the sound waves propagate in the phononic crystal were researched. An explicit dynamic analysis software LS-DYNA are used to analyze the mechanism of locally resonant phononic crystals'steady-state response. Finally, the main contents and conclusions of this article are as follows:(1) Comparing the numerical simulation results with experimental data test by Huajia , and comparing the core's first-order resonance frequency with first frequency band of Wang, show that using the finite element software LS-DYNA to simulate acoustic wave in phononic crystals is effective, and the finite element model is correct.(2) With reference to single-row core experimental model of Huajia, LS-DYNA software was used to simulate a single-frequency sound waves vertically incident phononic crystals, and the process of wave propagation phenomena and laws were summarized, and combined with theoretical analysis, shows that: The longitudinal wave propagation to the coating layer interface, then the modal shift, resulting in transverse and longitudinal waves. The coating and the core have a significant barrier to the sound waves spread the matrix, in which the role of coating layer is larger, the attenuation rate of before and after the location is 77%, while the same thickness uniformity plate attenuation value was 30%.(3) With reference to five-row core experimental model of Huajia, LS-DYNA software was used to simulate the vibration of different components while a single-frequency sound waves vertically incident phononic crystals, shows that: Front and rear cores'vibration velocity is little difference, while the vibration velocity of before and after location of the matrix is varied widely (about 97%); All the amplitude of cores decay gradually over time, while all the matrix is small amplitude decay with time. Traditional non-damped forced vibration equation is used to analyze the phenomenon of all the amplitude of cores decay gradually over time while all the matrix is small amplitude decay with time. And making a inference: Improve the insulation of two-dimensional ternary locally resonant phononic crystals should increase the difference between the matrix's natural frequencies and the sound wave frequency, while reducing the difference between the matrix's natural frequencies and the core vibration frequency. Finally a simplified model of two-dimensional ternary phononic crystal plate was established.