PHY23 Dispersion of Ultrasonic Waves (Lamb Waves)

Dispersion of Ultrasonic Waves (Lamb Waves) Investigation of the phenomenon of the generation and propagation of guided ultrasonic waves (Lamb waves) The experiment investigates the phenomenon of the formation and propagation of guided ultrasonic waves (Lamb waves). The frequency-dependent speed (dispersion) of Lamb waves in thin glass plates is measured, which are excited and recorded using angle probes. Keywords: Longitudinal waves, transverse waves, Lamb waves, wave modes, phase velocity, group velocity, dispersion, law of refraction The phenomenon of Lamb waves is caused by the superposition of longitudinal and transverse sound waves in thin plates whose thickness is smaller than the wavelength. It is interesting that Lamb waves show a frequency-dependent change in the speed of propagation (dispersion). Lamb waves also appear in the form of symmetrical and antisymmetrical modes that propagate independently of one another in the material. In the experiment, different Lamb wave modes