K. Maslov et al., A new technique for the ultrasonic detection of internal transverse cracksin carbon-fibre/bismaleimide composite laminates, COMP SCI T, 60(12-13), 2000, pp. 2185-2190
Through-transmission ultrasonic C-scan imaging with inclined focusing trans
ducers in confocal configuration has been used for the detection of partial
and internal cracks in a cross-ply, [0/90/0] carbon/epoxy laminate. A numb
er of partial cracks (intersecting only one edge of a coupon) as well as co
mpletely internal cracks were found ultrasonically after the sample was sub
jected to static loading. The validation of the result by cutting the sampl
e along two lines :in the 0 degrees direction and checking the presence of
the internal cracks with an optical microscope shows a good correlation bet
ween the ultrasonic image and the optical data. Experimental results show t
hat in the IM7/5250-4 composite, which contains a toughened BMI resin, init
iation of transverse cracks under static loading occurs with the formation
of partial cracks not necessarily originating at the edge of the sample. (C
) 2000 Elsevier Science Ltd. All rights reserved.