Monitoring of plate structures using guided ultrasonic waves

Efficient permanent nondestructive monitoring of the integrity of technical structures with structural features, e.g., stiffeners on the hull plates of a ship, can be achieved using arrays of distributed sensors for guided ultrasonic waves. The validity of the measurement concept is demonstrated experimentally and using Finite Element (FE) simulations for the first anti-symmetric Lamb wave mode A(0). The sensitivity for the detection and localization of defects is discussed and the influence of the number of sensors and the evaluation concept is studied. Good results have been found for the evaluation of measurements at a plate containing a part-through slot and synthetic FE data for a plate with a crack at a stiffener.