Tunable Digital Elastic Metamaterial

Elastic metamaterials are attractive in advanced engineering applications,such as vibration isolation,subwavelength focusing,waveguiding,thermal management and invisible cloaking.Elastic metamaterials with tunability can be adaptively controlled within different working frequency ranges,which broaden the applications of traditional elastic metamaterials.However,tunable methods to-date require sophisticated design and are a lack of multifunctional tunability.These problems make tunable elastic metamaterials hard to be manufactured and controlled.This thesis proposed a magnetic tuning method and designed a 3D printed tunable elastic metamaterial with magnetic control.The proposed tunable elastic metamaterial can realize the control of cells' configurations along with bandgap characteristics and waveguide paths.This thesis also proposed a design concept of digital elastic metamaterials with elastic metamaterial bits.The digital elastic metamaterial can realize programmable bandgap range and position.The main contents are listed below:1.A magnetic tuning method is introduced into a 1D spring-mass system,which can realize the configuration tuning of cells.The impact of the tuning method on system's band structures and transmission features is theoretically and experimentally studied.The magnetic tuning mechanism is explained through the study on cell's effective mass density.2.A 3D printed tunable elastic metamaterial with magnetic control is designed,which can realize the geometrical tuning of local resonators.Bandgap tuning is studied using finite element method.Tunable waveguides are realized both in the experiment and simulation.Tunable meta-surface and self-powering vibration isolation device are proposed.3.A concept of digital elastic metamaterials is proposed.Elastic metamaterial bits based on bandgap characteristics are designed.The influence of 1D and 2D sequences of metamaterial bits on bandgap width and position are studied based on tunable spring-mass system and tunable elastic metamaterial.