Propagation of A-waves in a plane plate : An experimental study

The propagation of the A-wave is investigated theoretically on a plane brass plate completly immersed in water or in contact with water on one side and air on the other side. The main characteristics of this wave are calculated: group and phase velocities as a function of frequency and energy distribution in a cross section of the plate. An experimental study is then exhibited for 200 mm long plane brass plates of various thicknesses (0.2, 0.1 and 0.05 mm) immersed or semi-immersed in water. Using a time frequency representation, the experimental group and phase velocities are measured versus the frequency thickness product (F.H). The experimental dispersion curves are very close to the theoretical ones.