Combinational design of linear and nonlinear elastic metamaterials

The properties and applications of linear elastic metamaterials have been widely exploited. The resonant bandgaps in linear metamaterials can suppress wave propagation, but they are narrow in nature. Nonlinear elastic metamaterials have attracted increasing attention in recent years and can provide effective methods for controlling elastic waves, such as the ultrabroad chaotic band. A combinational design of linear and nonlinear metamaterials may introduce ways to explore new properties, especially wave suppression. This paper numerically studies the characteristics of a combinational elastic metamaterial model. We compare the wave suppression of different combinational schemes and summarize the generic regularities. The effect of nonlinearity and amplitude-independent wave suppression in the metamaterial are clarified. We show that the combinational design can offer both bandgaps and chaotic bands, which greatly improves the robustness, efficiency and bandwidth for the wave suppression effect relative to linear or nonlinear metamaterials consisting of a single type of unit cell. The mechanisms for the wave reduction properties in the combined models are also studied. The combinational design can provide useful approaches for studies and applications of elastic metamaterials.