Research On Vibration Band Gap Properties Of The3-Dimensional Phononic Crystal With Parallelepiped Structures

Porous periodic lattice materials have some special acoustic performances and the band gap properties, so it is very important to research wave propagation characteristics of the lattice material, which will get the unexpected vibration damping and noise reduction effect in aerospace, aviation, navigation and other fields. The lattice materials have the advantages of light weight, high strength, sound absorption properties and porous characteristics, which can be filled in various types of energy absorbing, sound absorbing, microwave absorbing materials to achieve the structure-function combining composite materials. Three-dimensional phononic crystal parallelepiped structure is a3-dimensional lattice composite material structure, which is made by adding high damping materials and balls into the skeleton of periodic truss-like micro-structures. In this paper, taking3-dimensional phononic crystal parallelepiped structures for example, the main researches includes:Firstly, we adopt theoretical analysis to research the elastic wave band-gaps and damping properties of3-dimensional phononic crystal parallelepiped structures, by choosing a representative unit cell and using the finite element software ANSYS, MATLAB programming software, periodic structure and Bloch theory, we get the band structure curve, wave propagation attenuation coefficient curve and vibration damping ratio curve. From the curves we can clearly find the band-gap ranges of the structures. Secondly, we simulate the transmission characteristics of3-dimensional phononic crystal parallelepiped structures by the finite element method, we get vibration frequency response function curves. From the curves we can obtain the rough band-gap ranges. Comparing the two band-gap ranges, the conclusion shows the two band-gap ranges are almost same.Lastly, based on the correctness of the theory, we analyzed several kinds of parameters effects on the elastic wave band-gaps and damping properties of3-dimensional phononic crystal parallelepiped structures by changing the following several aspects:the structural shapes, combination of mass balls, combination of radius, the directions of wave propagation and rod materials. The results show that the structural shapes, the wave propagation directions will be great influence on the generation of the band gap; density sum of mass balls and radius of mass balls are bigger, the initial and final frequency are lower, the band-gap widths are wider and wave propagation attenuation coefficients are bigger, but the trends of decrease are flat; the elastic modulus of truss materials are smaller, the band-gap ranges are lower and the wave propagation attenuation coefficients are bigger.