On the influence of fatigue on ultrasonic polar scans of fiber reinforced composites.

Ultrasonic polar scans have already proved to be well-suited as a practical means of characterizing fiber reinforced composite plates. The method consists of registering the reflected or transmitted sound amplitude as a function of each possible angle of incidence. It is hence an amplitude measurement by which it differs from more common 'time of flight' measurements. Ultrasonic polar scans are actually a fingerprint of a composite laminate. One of the many promising applications of the ultrasonic polar scan is the monitoring of fiber reinforced composites in service. Especially the progress of fatigue damage can be monitored easily and nondestructively. This paper presents numerical simulations of the influence of fatigue on ultrasonic polar scans as well as some experimental results.