T. Ditchi et al., BROAD-BAND DETERMINATION OF ULTRASONIC-ATTENUATION AND PHASE-VELOCITYIN INSULATING MATERIALS, The Journal of the Acoustical Society of America, 94(6), 1993, pp. 3061-3066
Ultrasonic attenuation and phase velocity in a solid insulating materi
al are determined in a broad frequency band by studying the propagatio
n of a pressure pulse in a sample of this material submitted to an ele
ctric field of known value. During the propagation of the pulse in the
sample, which is placed between short-circuited electrodes, a current
is generated in the external circuit. This signal gives directly the
time dependence of the pressure pulses entering and exiting the sample
, from which the frequency-dependent attenuation and phase velocity ar
e deduced by Fourier analysis. The pressure pulse is generated by the
impact of a laser pulse on an absorbing surface adjacent to one face o
f the sample. New results obtained in polyethylene and silicone sample
s are presented. The proposed method presents the following advantages
: It avoids the use of a transducer, reduces the impedance matching re
quirements, and provides information in a broad frequency band by a si
ngle measurement.