The Band Gap Characteristic Of Phononic Crystals And Its Application Study In Antisound

As new composite functional materials, Phononic crystals (PCs) have been discovered less than 20 years. However, because of their fantastic property of elastic band gap (EBG), PCs have been carried out a number of experimental and theoretical studies home and abroad. The EBG makes the PCs possess potential applied values in such civil or defence-related fields as signal control, sound insulation, vibration control, precision machining.In chapter 1, we make an investigation for relational research situation of PCs, and then we describe the main ingredients of the finite difference time domain (FDTD) method in chapter 2. We go through the problems such as numerical stability and numerical dispersion, absorbing boundary conditions, periodic boundary conditions in FDFD algorithms on the calculating of EBG, finally, where a good agreement with the used measurement.Next, we devote to the study of band gap performance of PCs in chapter 3. We involve the study in the EBG character of cylinders immersed in air, and give numerical simulations to the attenuation characteristics of elastic waves propagating in PCs, a periodic influence on the generating of EBG and whose performance through combination PCs.In chapter 4, the application explore of PCs is taken into analysis in antisound field. As a brand-new task, properties of frequency selection and waveguide are used, and special performances are introduced by simulations.In short, with the work on FDTD algorithm, based on numerical analysis of EBG performance, the paper makes an intensive study of PCs about their EBG characters. It makes the Influencing factors of EBG more clearly and introduced PCs in antisound, which is grateful that we have gained some achievement in the field of the special antisound.