Adjoining of negative stiffness and negative density bands in an elastic metamaterial.

In this paper, we explore an elastic metamaterial adjoining the frequency band of negative density and that of negative stiffness. If the band-adjoining occurs, a fully continuous widened stop band covering the entire ranges of the negative density and stiffness can form. The resulting stop band can be useful for various vibration applications such as vibration shielding. We show that the bandadjoining frequency is characterized by a standing wave with peculiar "unbalanced" motions. Experiments with the symmetric Lamb waves were conducted to validate the theoretical prediction and the effects of perturbed adjoining band on wave physics are also investigated. [ABSTRACT FROM AUTHOR]