DocumentCode :
1655347
Title :
Experimental study of anisotropic and dispersive effects on carbon-epoxy composite using laser generated ultrasound
Author :
Corbel, C. ; Guillois, F. ; Royer, D. ; Fink, M. ; Mol, R. De
Author_Institution :
Lab. Ondes et Acoustique, Paris 7 Univ., France
fYear :
1992
Firstpage :
801
Abstract :
New contactless techniques using laser-generated ultrasound are applied to the inspection of composite materials. Experimental results are obtained with a 1-μs pulse dye laser excitation and a piezoelectric detection on half cylindrical composite samples. The measurements are taken in two different lay-up design composites (carbon/epoxy: unidirectional and cross-ply 0°/45°/90°/-45°). Angular directivity patterns of quasi-longitudinal, quasi-shear, and shear waves are presented. Velocities of the different types of waves simultaneously generated are compared to the phase and group velocities computed using Christoffel equations and a hexagonal mode. It is shown that with this point-source measurement technique the wavefront arrival times agree with the group velocity rather than with the phase velocity. At higher frequencies, a large dispersive effect for the longitudinal and shear elastic waves propagating along the plies of the cross-ply composite is emphasized. Experiments performed in the frequency range of 0.5-4 MHz show velocity variations from 5600 to 2200 m/s (3600-1600) for longitudinal (shear) waves
Keywords :
acoustic wave production; carbon fibre reinforced plastics; inspection; laser beam applications; photoacoustic effect; ultrasonic materials testing; 0.5 to 4 MHz; 5600 to 2200 m/s; C; C fibre reinforced epoxy; Christoffel equations; NDT; anisotropic effects; contactless techniques; dispersive effects; half cylindrical composite samples; hexagonal mode; inspection; laser generated ultrasound; lay-up design composites; piezoelectric detection; point-source measurement technique; quasi-longitudinal waves; quasi-shear waves; shear waves; wavefront arrival times; Anisotropic magnetoresistance; Composite materials; Differential equations; Dispersion; Frequency; Inspection; Laser excitation; Optical pulses; Ultrasonic imaging; Ultrasonic variables measurement;
fLanguage :
English
Publisher :
ieee
Conference_Titel :
Ultrasonics Symposium, 1992. Proceedings., IEEE 1992
Conference_Location :
Tucson, AZ
Print_ISBN :
0-7803-0562-0
Type :
conf
DOI :
10.1109/ULTSYM.1992.275874
Filename :
275874
Link To Document :
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