Broadband Lamb wave measurements in aluminium and carbon/glass fibre reinforced composite materials using non-contacting laser generation and detection

Broadband measurements of Lamb wave dispersion characteristics have been performed in aluminium, carbon and carbon/glass fibre hybrid composite materials using a non-contacting optical technique. A high powered Q-switched Nd:YAG laser was used to initiate the Lamb wave spectrum in the materials: and an optical fibre Michelson interferometer was used to monitor the out-of-plane displacements associated with the propagating modes. Comparison of experimental results with theoretical modelling in both the aluminium and composite samples indicated good agreement for the excited modes. The application of this technique to the non-destructive testing and elastic property measurement of composite materials is discussed. (C) 1997 Elsevier Science B.V.