A0 mode interaction with a plate free edge: theory and experiments at very low frequency by thickness product.
When a plane acoustic wave reaches a medium with an impedance infinite or null, it experiences a phase shift of zero or pi and its amplitude on the edge is maximum or vanishes. The case of a flexion wave (A0 Lamb wave) at a free end is also simple; its amplitude is multiplied by a factor 2 square root 2 and the phase shift is pi/2. The evanescent wave at the origin of these phenomena, perfectly described by the classical flexural plate theory, is identified as the imaginary A1 mode of the exact Rayleigh-Lamb theory. The experiences confirm the theoretical predictions.
Ribay
Guillemette
G
Laboratoire Ondes et Acoustique, Université Denis Diderot, UMR CNRS 7587 ESPCI, Paris Cedex 05, France. guillemette.ribay@loa.espci.fr
Catheline
Stefan
S
Clorennec
Dominique
D
Ing
Ros Kiri
RK
Fink
Mathias
M
D000162:Acoustics; D005583:Fourier Analysis; D006801:Humans; D008962:Models, Theoretical; D013016:Sound; D013017:Sound Localization; D014465:Ultrasonics