Theoretical Aspects of Applying Lamb Waves in Nondestructive Testing of Anisotropic Media

Dirac cones in three-layered plates

“…The current research reveals that at any (positive) Poisson's ratio the Dirac-like cones emerge in three-layered plates made of layers having the same Poisson's ratios, as the inner core, while other physical properties satisfy the so called Wiechert condition. [27][28][29][30][31] It is revealed, that these Dirac-like cones arise at virtually any q2(1;∞), and sufficiently thick outer layers h outer >0.1, while the thickness of the inner layer is taken h inner =1. It should also be noted that in view of equations (1.3), (1.7) the bulk wave velocities in the layers coincide regardless of the q value.…”

“…While Dirac-like cones in acoustics can potentially play the same role in energy transmissions, as electromagnetic wave energy transmission in graphene, 26 the application of Dirac-like cones in acoustics is restricted by the necessity to satisfy either discrete relations (1.5), (1.6) for Lamb waves in homogeneous plates, 17 or to consider plates with transverse continuous variation of physical properties, where Dirac-like cones may appear at any Poisson's ratio. 25 The current research reveals that at any Poisson's ratio the desired Dirac-like cones emerge in three-layered plates made of layers having the same Poisson's ratios, and other physical properties satisfying the so called Wiechert condition: [27][28][29][30][31]…”

Head Waves in Modified Weiskopf Sandy Medium

“…SP waves are also the subject of extensive studies on the acoustics of layered composites [22,23]. In this respect, also see applications of energy dissipation for SP head waves along with Rayleigh, Rayleigh-Lamb, and other types of SAWs [24][25][26][27][28].…”

Abnormality of the longitudinal Pochhammer–Chree waves in the vicinity of C2 phase speed

“…Pochhammer–Chree waves in stratified cylinders made of coaxial cylindrical tubes in a contact can be studied by applying either the transfer matrix method (Ilyashenko and Kuznetsov, 2017) or the global matrix method (Cawley, 2001; Lowe, 1999; Rose, 1999). In the case of a homogeneous cylinder, both these methods lead to the same dispersion equation introduced in Section 3.…”