Analysis Of Vibration Isolation Characteristics Of Nonlinear Periodic Metastructures

Periodic structures are widely used in various fields of engineering,such as the traditional linear periodic structures represented by stiffened beam-plate structures,periodic honeycomb structures,and the new linear periodic structures represented by phononic crystals and photonic crystals.These structures not only bring us infinite aesthetic sense in vision,but also provide good wave propagation and vibration isolation characteristics.Nowadays,the nonlinear periodic structures which are composed of various nonlinear elements are gradually becoming a cutting edge research.This paper summarizes the research status of metamaterials,linear and nonlinear periodic structures,and analyzes the research results of scholars from various countries.On this basis,the bistable nonlinear element is added to the periodic structure to analyze the vibration absorption and isolation characteristics of the structure.Firstly,the static and dynamic characteristics of a single degree-of-freedom model with the bistable nonlinear element are analyzed.Then the nonlinear elements are connected in series to form a periodic cell,and the mechanical characteristics of it are analyzed.Secondly,the cell composed of negative stiffness bistable nonlinear element and some positive stiffness nonlinear elements are respectively connected in series to two-period nonlinear periodic structures,and their vibration absorption and isolation characteristics are calculated.Finally,static and dynamic experimental studies on the nonlinear element and the nonlinear periodic cell are carried out,and the experimental results are compared reasonably well with the theoretical results.It is found that the nonlinear bistable springs that constitute the basic elements of a single-degree-of-freedom nonlinear metamaterial element have two potential wells and a potential barrier;Nonlinear elements with bistable structure have force,displacement,potential energy and stiffness adaptability,and have metastructure characteristics of negative stiffness;Compared with nonlinear elements,the mechanical properties and metastructure properties of nonlinear periodic cell are more excellent.In terms of vibration attenuation and vibration isolation,the positive stiffness nonlinear periodic structure and the negative stiffness nonlinear periodic structure have a low frequency band attenuation range in addition to the main attenuation range inherent in the traditional periodic structure,compared with traditional linear periodic structures,both positive and negative stiffness nonlinear periodic structures have outstanding vibration reduction and filtering characteristics,and will have more extensive applications in the future.