Nondestructive testing of polyaramide cables by longitudinal wave propagation: Study of the dynamic modulus

It has been observed that cables at different states of fatigue had their o wn speed of longitudinal propagation of acoustic waves (1). This speed can be measured with piezoelectric captors and is proportional to the square ro ot of the sonic modulus. Our experiments, which have been carried out on Te chnora cables of diameter 2 mm, show that the modulus obtained from the wav e speed has the same behavior in fatigue as the modulus obtained from tensi le tests. Furthermore, our experiments also show that the residual strength in the cable is proportional to the modulus. A nondestructive control of c ables can hence be made from these sonic modulus measurements.