Application of neural networks to laser ultrasonic NDE of bonded structures

The purpose of this study is to develop artificial neural networks for the nondestructive evaluation of a bounded structure using laser generated surf ace waves. The radial basis model is employed and the inputs of the network s are the sampled dispersion curves while the output is the thickness of th e bonding layer or unbond ratio. Numerical simulated dispersion curves with noises were used to train and test the neural networks. The dispersion cur ves of laser ultrasonic experiments acquired by spectral analysis method we re also utilized to test the systems. For comparison, simplex inverse metho d was also introduced. The results demonstrate that neural networks are wel l suited for online evaluation of bonding thickness and unbond ratio of a b onded layered structure. (C) 2001 Published by Elsevier Science Ltd.