Experimental study of sound propagation in a chain of spherical beads

In this paper are described experimental observations which are concerned b y the propagation of pulsed ultrasonic waves transmitted through a limited one dimensional periodic granular medium submitted to a static force. This study-which is limited to a time domain analysis-exhibits experimental resu lts which depend on the polarization of the acoustic excitation. In the cas e of compressional excitation, spherical Rayleigh type surface waves propag ate around the beads. In the case of shear excitation, the experimental rec ordings point out the existence of a very low signal, the frequency of whic h is equal to the cut-off frequency of the chain. Moreover it is establishe d that the frequency value varies with the radius of the bead, the normal f orce applied to the beads, and the mechanical properties of the material. ( C) 2000 Acoustical Society of America. [S0001-4966(00)01610-6].