On infinite group velocity in composite plates

The analytical and geometrical conditions for the possible appearance of the infinite group velocity (IGV) points belonging to the dispersion curves of Lamb waves propagating in traction-free plates are studied by a combined method comprising Cauchy sextic formalism and the exponential fundamental matrix method. According to the obtained geometrical condition, the IGV corresponds to the coincidence of a tangent line to any of the dispersion curves with a straight line passing through the origin. The developed technique is demonstrated by applying to the analysis of Lamb wave dispersion in three-layered plates with a soft inner core.

Automated summary

The analytical and geometrical conditions for the possible appearance of infinite group velocity (IGV) points belonging to the dispersion curves of Lamb waves propagating in traction-free plates are studied. The study utilizes a combined method comprising Cauchy sextic formalism and the exponential fundamental matrix method. The obtained geometrical condition states that the IGV corresponds to the coincidence of a tangent line to any of the dispersion curves with a straight line passing through the origin.