Low-Frequency Steady-State Response Of Two Dimensional Phononic Crystals

Noise pollution has become one of the three major pollution in the world today alongwith the development of society and science in which the harm of Low-frequency noisepollution is particular outstanding. Noise pollution affects people's daily life seriously inhearing, relaxing, communication and psychological. So high-efficiency environmentalprotection product is in urgently needed. Traditional sound insulation materials hasmake a contribution to environmental protection. But it still can't meet people'srequirements. The appearance of phononic crystals is good news to us. Phononiccrystals are periodic composite material or structure with elastic wave band gaps whichhave low-frequency band-gap. The application prospect of phononic crystals iswonderful. The research about P.C.(phononic crystals) is necessary. There isn't anystudy in the field of low-frequency steady-state response of two dimensionalternarylocally resonant P.C. at present time. So we have much to do. Something whichis mentioned are studied in this article through finite element method(FEM) andLS-DYNA. Something is obtained like below.(1)Model verification is done in this article. A one dimention finite element model isdesigned and the result from this method is contrasted with that of theory. We found thatit's anastomotic. This can provide basis for the study of low-frequency P.C. throughFEM.(2)Look for the best model of P.C. through studying different rows of coreexperimental model. We find that the attenuation of wave in single-row coreexperimental model is 30%. And that in three rows, five rows and seven rows is 32%,75% and 77%. Obviously, the result is the best in practical application when number ofcore is five. The reason is expressed in the article.(3)Low-frequency steady-state response of two dimensional ternarylocally resonantP.C. have been studied in the last chapter. We analysis the effect of each component inP.C. The vibration attenuation of back side points contrasted whit front side points inmatrix is 30%. So we have conclusion that sound wave propagates through matrixmainly. The vibration attenuation of the back cores contrasted to the front cores is 75%when that of integuments is 90%. That is to say cores and integuments are at animportant position in P.C. The decay phenomenon of each component is analysed in thisarticle. A formula is obtained which can direct people to establish a appropriate modelthrough changing materials parameter and structure parameter of cores.