Determining Mechanical Properties of Cardboard from Photoacoustic Lamb Wave Transmission Data
Laser-generated transient Lamb waves have been proven to be a useful tool for determining thin plate thickness and elastic constants. The measurement relies on the wide range of frequencies generated by the thermoelastic or ablation laser source . The dispersion relation of the lowest Lamb-wave modes can be determined using established signal processing techniques. Usually the Lamb-wave packet propagating on a plate is observed using for example a) a contact “wedge” transducer, b) by observing the leakage of energy in directions where the k-matching condition is fulfilled or c) an interferometer, d) with near-field microphones with spatial periodicity on the sensitive surface to pick a particular wavelength [2,3,4,5]. The last three of these methods are non-contacting and therefore attractive for practical applications.
KeywordsPhase Velocity Lamb Wave Typical Waveform Spatial Periodicity Lamb Wave Generation
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- 1.R.J. Dewhurst, C. Edwards, A.D.W. McKie, and S.B. Palmer, Appl. Phys. Lett. 51 (14), 5 October 1987.Google Scholar
- 2.M. Luukkala, P. Meriläinen, Metal plate testing using airborne ultrasound Ultrasonics, IPC Science and Technology Press Ltd, Guilford, England, UK September, 1973.Google Scholar
- 3.I.A. Viktorov, Rayleigh and Lamb Waves; Physical Theory and Applications, Plenum Press, New York (1967).Google Scholar
- 4.C.B. Scruby and L.E. Drain, Laser Acoustics; Tecniques and Applications, Adam Hilger, Bristol 1990.Google Scholar
- 5.C. Edwards, A. Al-Kassim and S.B. Palmer, Rev. of Progress in Quantitative Nondestuctive Evaluation, Vol 12, Plenum Press, New York, 1993.Google Scholar