Elastic metamaterials with simultaneously negative effective shear modulus and mass density

Phys Rev Lett. 2011 Sep 2;107(10):105506. doi: 10.1103/PhysRevLett.107.105506. Epub 2011 Sep 2.


We propose a type of elastic metamaterial comprising fluid-solid composite inclusions which can possess a negative shear modulus and negative mass density over a large frequency region. Such a material has the unique property that only transverse waves can propagate with a negative dispersion while longitudinal waves are forbidden. This leads to many interesting phenomena such as negative refraction, which is demonstrated by using a wedge sample and a significant amount of mode conversion from transverse waves to longitudinal waves that cannot occur on the interface of two natural solids.