Research On The Vibration Band Gaps Of Concave-convex Phononic Crystals

Harmful vibration in pipeline system damages the physical and mental health of mankind seriously,shortens the service life of equipments and affects the concealment performance of ships.The traditional vibration reduction methods for pipeline are difficult to control the vibration in low frequency range because of the limitation of material and technology.Phononic crystals are periodic structures or materials,which are manually compounded.Their band gaps can regulate the propagation of elastic waves in media.A large number of studies shown that the application of the theory of phononic crystals to the vibration control is a new and effective way to achieve pipeline vibration reduction.One-dimensional phononic crystals have simple structure,broad application and high application value.In order to obtain phononic crystals with excellent band gaps,One-dimensional phononic crystals called concave-convex phononic crystals are designed in this paper.In order to overcome the shortcomings of the traditional ways to reduce the vibration of pipeline,and suppress bending vibration in low frequency range,the concave-convex phononic crystals are applied to the vibration control of pipeline system.The main contents of this paper are as follows:(1)Design of Concave-convex Phononic CrystalsBased on the structural characteristics of waveform springs,the concave-convex microstructure is constructed.Moreover,referring to the theory of phononi c crystals,we design a kind of one-dimensional phononic crystals with concave-convex microstructures,named concave-convex phononic crystals,and establish the cell structure model and the whole structure model.(2)Analysis of Concave-convex Phononic CrystalsThe band structure and transmission characteristics of concave-convex phononic crystals are calculated.In addition,the band structure and frequency response curves are analyzed comprehensively and the reliability of finite element software calculation is proved.A kind of phononic crystals without concave-convex microstructures are established,which are the through-hole cylindrical phononic crystals.What's more,the band structure and transmission characteristics of through-hole cylindrical phononic crystals are calculated.The band gaps of concave-convex phononic crystals are compared with through-hole cylindrical phononic crystals,which prove that concave-convex phononic crystals have better vibration band gaps.The influence of structural parameters of concave-convex phononic crystals on band structure are analyzed,which provide a basis for designing band gaps artificially.(3)Analysis of Damping Performance of Concave-convex Phononic Crystals IsolatorConcerning the bending vibration of pipeline system in low frequency range,referring to the influence of the structural parameters of concave-convex phononic crystals on the band structure,we design the damper of concave-convex phononic crystals.The damping performance of concave-convex phononic crystals shock absorber are analyzed.the results show that the concave-convex phononic crystals shock absorber has a good effect on reducing the bending vibration of pipeline system in the low frequency range.We analyze the influence of the number of periods on the transmission characteristics of concave-convex phononic crystals isolator.The results show that the more period number of concave-convex phononic crystals isolator,the damping effect is better.