Wave Motion In Periodic Structure Containing Double Resonators

The periodic structures can be used to suppress the elastic wave propagation in a certain frequency range,and show great application potential in vibration reduction.The periodic structure based on the mechanism of local resonance has become the frontier in mechanics,acoustics,materials science and engineering.In this thesis,A two-dimensional periodic structure with double resonators was designed based on the local resonant mechanism.The wave characteristics of the unit with double-resonators are studied by both finite element analysis and vibration experiment.The main research results of this thesis are as follows:(1)A double resonators structure with new vibration mode is introduced for element design.Compared with the periodic structure with the same geometry and material parameters,the band gap of the two-dimensional periodic structure with double resonators is appeared at lower frequency range.The finite element method is used to optimize the parameters of the structure.The band gap characteristics of the optimized periodic structure are analyzed.(2)A surface layer is used to control the band gap characteristics of the periodic structure.The band gap characteristics of the period structure with surface layer is obtained.(3)The 3D printing technology is used to the manufacture of periodic structures.The vibration experiment for the period structure with double resonators is carried out.The experiment results coincide well with the finite element analysis.The first five natural modes of the out-of-plane vibration are obtained.Keeping away from these frequencies can avoid the influence of out-of-plane resonance.(4)Both the finite element analysis and the vibration experiment show that the small change of the thickness of horizontal beam can cause a significant change in the band gap characteristics,which can be used to control the band gap characteristics of periodic structures.