The Study On Vibration Reduction Characteristics And Band Gap Optimization Of Phononic Crystals

Phononic Crystal(PC)is a new type of functional material in the past two or three decades.PC consists of materials arranged periodically in a particular direction with a cell as the smallest unit and a lattice constant as the basic size.Its characteristics include: defect state characteristics,negative refraction,acoustic focusing and band gap(BG)characteristic.In this paper,the BG characteristic is discussed.The BG characteristic shows that when elastic waves in a certain band pass through PC,it will cause a great attenuation and can not propagate normally,while the elastic waves in other frequency bands can pass through normally.BG characteristic in practical applications reflects the characteristic of vibration reduction has broad prospects for design.In this paper,we first introduce the research status of PC in the past twenty years,the research results of PC by many excellent researchers are summarized,the research direction and the focus issues to be explored are pointed out.Based on many research results,different structural models in this paper are calculated with different research methods,the validity of the theoretical research is verified by the experimental results of the existing literature.Different structures combined with different research methods to obtain the BG results,reflecting The completeness of the theoretical basis of PC.In this paper,we take the lattice PC as an example to explore deeply.A large number of numerical simulations are carried out for the factors affecting the BG of Bragg scattering PC.The main influencing factors include physical and geometric parameters are found.At the same time,a large number of examples are summarized to obtain the influence of these main influencing factors on the BG.The function is fitted to the result and the corresponding function curve is obtained.The basic influence law of Bragg scattering PC is expressed in mathematical form,which provides some guidance for the design of PC.At the same time,considering the geometric parameters,the BG of PC with lattice structure is explored under the same porosity.The optimal combination of parameters is obtained by combining the optimization algorithm,then the structure design with the maximum BG is obtained.In the end,a novel lattice structure is formed by changing the porosity of the PC with zig-zag lattice structure as the initial design.The effect of porosity on the BG of PC is further explored,which further enlarges the BG of PC and provides a new idea for the design of PC to maximize the BG.The influence of structural periodicity on the attenuation of BG is also explored in this paper.It is found that the greater the structural periodicity,the more obvious the attenuation of elastic wave is.The effect of periodicity on the attenuation degree should be taken into account in the design of practical applications.This paper has some reference value for the design of PC,the control of BG and the optimization of PC structure.