Anisotropic elastic metamaterials for novel wave manipulation: a review

Elastic waves are crucial in non-destructive testing and evaluation across industrial and medical fields. While elastic metamaterials have been extensively studied for elaborate wave manipulation, those exhibiting isotropic or orthotropic behavior often fail to achieve certain elastic wave phenomena involving coupled normal and shear deformations. Therefore, their applicability is limited in many practical contexts. To overcome these limitations, elastic metamaterials with extraordinary anisotropy—exhibiting properties not found in nature—have emerged as a promising solution. This paper elucidates the fundamental design principles of anisotropic elastic metamaterials and their applications for unconventional wave manipulation.