Patent ID: 6899519
Filing Date: 2005-05-31
Classification: G01N

Abstract:
1. A method of detecting a change in the structure of a complex shape article comprising the steps of injecting an ultrasonic signal into the complex shape article at a first position to produce a diffuse field ultrasonic signal in the complex shape article, detecting the diffuse field ultrasonic signal in the complex shape article at a second position, measuring the time for the diffuse field ultrasonic signal to travel from the first position to the second position, comparing the measured time for the diffuse field ultrasonic signal to travel from the first position to the second position with a stored time for the diffuse field ultrasonic signal to travel from the first position to the second position, and determining if there is a change in the time for the diffuse field ultrasonic signal to travel from the first position to the second position, which is indicative of a change in the structure of the complex shape article wherein the complex shape article comprises a rotor comprising a plurality of axially spaced rotor discs, the axially spaced rotor discs being acoustically connected by a plurality of propagation paths.