A New Inverse Method of Elastic Constants for a Fiber-ReinforcedComposite Plate from Laser-Based Ultrasonic Lamb Waves

A new inverse method based on the wavelet transform and the artificial neural networks (ANN) is presented to recover elastic constants of a fiber-reinforced composite plate from the laser-based ultrasonic Lamb waves. The transient waveforms obtained by numerical simulations under different elastic constants are taken as input of the ANN for training and learning. The wavelet transform is employed for extracting the eigen-vectors from the raw Lamb wave signals so as to simplify the structure of the ANN, then these eigen-vectors are inputed to a multi-layer internally recurrent neural network with back-propagation algorithm. Finally, the experimental waveforms are used as the input in the whole system to inverse elastic constants of the experimental material.