Wave propagation in thin Plexiglas plates: implications for Rayleigh waves

Two-dimensional (2D) experimental models are often used to study wave propa gation problems. The advantages of using 2D experimental models, as opposed to 3D models, is the reduction of both extraneous reflections and mathemat ical complexity. Further, many structural elements conform to this geometry . The following study examines Rayleigh wave motion in thin Plexiglas sheet s. Source-receiver time domain measurements were made at different location s on the Plexiglas sheet. The time-distance space was 2D-Fourier transforme d into the frequency-wavenumber space to facilitate the analysis of wave mo des propagating in the Plexiglas sheet. Experimental results showed that fu ndamental symmetric (S-0) and antisymmetric (A(0)) Lamb waves propagated th rough the plate. Along the thickness of the plate, a nondispersive Rayleigh wave was generated. Lamb waves were found to interfere with the Rayleigh w ave. The assumption of generalized plane stress is preserved if higher mode Lamb waves have low energy content. (C) 1999 Elsevier Science Ltd. AU righ ts reserved.