Study The Transmissions Of Phononic Crystals And Composite Materials Based On Finite-difference Time-domain

Recently,the study of elastic and acoustic wave simulation in periodic elastic composite materials and the phononic crystals is a new acoustic materials which has attracted much attention.Phononic crystals(PCs)is a new concept put forward with the analogy of photonic crystals which use the energy band theory to study the classical wave in artificial periodic structure.Phononic crystal is a new type of acoustic materials,the essential characteristics of phononic crystal is band gap,which property makes a potential application in engineering fields.According to the different scatterer cycling arrangement in the phononic crystals which can be divided into three kinds as one-dimensional,two-dimensional and three-dimensional phononic crystals.While,according to band gap aroused by the distinct physical mechanism of phononic crystals which are classified into two categories:the Bragg scattering band gap and the locally resonant band gap.The two band gaps physical mechanism are different,but the internal is unity.The phononic crystals have a very wide range of research area and the research tools for it are various and convenient.We can get the band gap of the photonic crystals both from the experimental measurement and commercial software simulation.Now with the help of numerical simulation to simulate various physical properties of phononic crystal is very useful.The numerical methods such as the transmission matrix method(TMM),the plane wave expansion method(PWE),the time domain finite element method(FEM).This paper mainly concentrate on the finite-difference time-domain method(FDTD),main feature of the method is difference approximation,as a fast and effective algorithm,recently the analysis of FDTD have been applied to the phononic crystals.In this paper,based on the FDTD method,the related transmission coefficients properties of one-dimensional periodical phononic crystals are calculated,which providing a simple method for the research of phononic crystals;then,considering the three kinds of the designed one-dimensional phononic crystals,as the different phononic crystals filling rate,the different phononic crystals lattice constant and the different scattering to analysis the different phononic crystals.Last,the one-dimensional quasi-periodical phononic crystals and the one-dimensional three-component phononic crystals are also simulated,and the different band gaps of two structures with normal phononic crystals are calculated and discussed,with the different band gap of them we can analysis the artificial composite materials.All in all,using the FDTD to provide a new kind theoretical analysis and numerical simulation to analysis the band gap and to design of acoustic devices.