Acoustical Surface Characterization of PP/OWF Composite Plates
Résumé
Polypropylene polymer (PP) combined with olive wood flour (OWF) reinforcement is studied in view to find an optimum of viscoelastic properties. The flour ratio content is varied from 0 to 30% and its influence is characterized in terms of surface homogeneity and in terms of acoustic impedance. This acoustical surface property is closely related to the wavelength and active area of the used transducer if it is a plane one. In case of a focused transducer, the wavelength is also a key parameter as well as the so-called f-number which is the ratio between focal distance and active diameter. The focal spot size is thus the surface from which the average acoustical impedance property can be evaluated. The effective wave velocity is deduced from time-of-flight measurements and combined with the average acoustical impedance in order to deduce the effective surface averaged density. As a result, some C-scans of specular echoes obtained for a given PP/OWF composition are compared as a function of the center frequency. The distribution of these acoustical surface properties is compared and discussed for various compositions, depending on the chosen transducer. The influence of the surface roughness is also discussed as an influencing parameter. The analysis of those experimental results constitutes a tool for the improvement of the fabrication process.
Domaines
Acoustique [physics.class-ph]
Fichier principal
2020-11-17 - Acoustical impedance - Template FA2020.pdf (1.22 Mo)
Télécharger le fichier
Origine | Fichiers produits par l'(les) auteur(s) |
---|