effective parameter identicafation of 2d structures from measurements

Jun 25, 2004 - For specific materials, it is necessary to know the dispersion curve associated with the flexural waves, particularly in the case of anisotropic ...
Télécharger le PDF
23KB taille 3 téléchargements 209 vues
commentaire
Report
6th International Conference on Vibration Measurements by Laser Techniques (Proc. SPIE vol. 5503), Ancona (Italy), 22-25 June 2004, 169-176. (http://www.aivela.org/general.htm)

EFFECTIVE PARAMETER IDENTICAFATION OF 2D STRUCTURES FROM MEASUREMENTS USING A SCANNING LASER VIBROMETER

Jean-Claude Pascal (a), Jing-Fang Li (b), Xavier Carniel (c) (a)

Laboratoire d'Acoustique de l'Université du Maine (UMR CNRS 6613) and Ecole Nationale Supérieure d'Ingénieurs du Mans (ENSIM) Université du Maine, rue Aristote, 72000 Le Mans, France. Email: [email protected] (b)

Visual VibroAcoustics, 51 rue d'Alger, 72000 Le Mans, France Email: [email protected] (c)

Centre Technique des Industries Mécaniques (CETIM) 52 avenue Felix-Louat, BP 80067, 60300 Senlis, France, Email: [email protected]

ABSTRACT For specific materials, it is necessary to know the dispersion curve associated with the flexural waves, particularly in the case of anisotropic composite materials whose parameters are not known a priori. The method described here is based on energy concepts. It uses the vibration velocity measured by scanning laser Doppler vibrometer. The Spatial Fourier Transform (SFT) of vibration velocity field is used to compute the spatial derivatives of velocity which are then used to obtain energy quantities. The dispersion curve and the loss factor are computed from these quantities. It is shown that the use of these energy quantities leads to results independent to the analysis resolution in the wavenumber space, contrary to the direct extraction obtained by looking for the maximum values in the phase spectrum. The pre-processing allows one to eliminate the disturbances brought by the mechanical excitation zones and plate edges. Furthermore, the mechanical parameters for plane structures such as dynamic stiffness and loss factor, are estimated by this technique. This method can be extended to orthotropic and anisotropic structures. Experimental results are presented. Keywords: Optical measurements, Scanning laser vibrometry, dispersion curve, loss factor, wavenumber processing, structural intensity