Observation of dispersion behavior of acoustic wedge waves propagating alone the tip of a circular wedge with laser ultrasonics

This research is focused on measuring the dispersion behavior of acoustic wedge waves propagating along the tip of circular wedges with a laser-generation/laser-detection laser ultrasound technique. The unexpected measurement results indicate that the dispersion relation of the fundamental antisymmetric flexural (ASF) mode has a negative slope in the phase velocity-frequency dispersion space for a nearly truncation-free circular wedge. It is also observed that, at the low-frequency, or long-wavelength limit, the fundamental ASF mode of the circular wedge has a phase velocity higher than that of a straight wedge due to the curvature effect. However, at the high-frequency, or short-wavelength limit, the fundamental ASF mode of the circular wedge becomes insensitive to the curvature effect and is dominated by the truncation effect.