Dirac Cones in the Propagation of Lamb Waves in a Functionally Gradient Layer

S. G. Saiyan^a^,* and S. V. Kuznetsov^b^,**

^aNational Research Moscow State University of Civil Engineering, Moscow, 129337 Russia

^bIshlinsky Institute for Problems in Mechanics, Russian Academy of Sciences, Moscow, 119526 Russia

*email: Berformert@gmail.com
**email: kuzn-sergey@yandex.ru

Received May 26, 2025

Abstract— The appearance of proper and degenerate Dirac cones during the propagation of Lamb waves in an isotropic functionally graded layer satisfying the Wiechert condition is analyzed. It has been revealed that Dirac cones appear in a layer, in which the distribution of physical properties is asymmetric with respect to the midsurface and in any Poisson’s ratio. The study is based on the Cauchy formalism and the exponential fundamental matrix method.

Keywords: Lamb wave, Dirac cone, dispersion, Cauchy formalism

DOI: 10.1134/S1063771025600548