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An experimental evaluation of two effective medium theories for ultrasonic wave propagation in concrete
We have analyzed the longitudinal wave propagation in a heterogeneous medium-like concrete including elastic or fluid scattering particles. The evolution of the phase velocity and attenuation have been computed with two homogenization models (WT and GSCM) over a wide range of frequencies, as a function of the volume ratio and size of spherical scattering particles. An experimental validation study has allowed each of these models to be qualified with respect to changes in concrete. Both models have shown different potential, with the GSCM appearing to be the most suitable for describing elastic solids containing elastic scattering particles, whereas the WT model allows cavities to be taken into account. The observed frequency limits are found to be in good agreement, up until ka values of the minimum order of 1.5 for the velocity and for the attenuation. Both models have shown good potential in representing the two types of scatterers. The key to modeling improvements may lie in the coupling of these two models by way of an incremental approach to their representation for different types of scattering particles. A first step can be the modeling of concrete composition by elastic inclusions in a cement matrix with the GSCM model to obtain an equivalent homogeneous medium. Then this equivalent medium can be used like a matrix for the second step, including spherical cavities with the WT model to take into account damage in concrete. Thus, with these two steps, one can reach a high volume fraction of obstacles in the elastic matrix. This outcome allows the use of these models to be validated in media with a very high scattering particles volume fraction for the prediction of phase velocity and attenuation but neglecting multiple scattering effects between the two types of scatterers. Another way to improve ultrasonic nondestructive characterization of heterogeneous media with high particle concentration can be conducted using a model which integrates mode conversion.
An experimental evaluation of two effective medium theories for ultrasonic wave propagation in concrete
We have analyzed the longitudinal wave propagation in a heterogeneous medium-like concrete including elastic or fluid scattering particles. The evolution of the phase velocity and attenuation have been computed with two homogenization models (WT and GSCM) over a wide range of frequencies, as a function of the volume ratio and size of spherical scattering particles. An experimental validation study has allowed each of these models to be qualified with respect to changes in concrete. Both models have shown different potential, with the GSCM appearing to be the most suitable for describing elastic solids containing elastic scattering particles, whereas the WT model allows cavities to be taken into account. The observed frequency limits are found to be in good agreement, up until ka values of the minimum order of 1.5 for the velocity and for the attenuation. Both models have shown good potential in representing the two types of scatterers. The key to modeling improvements may lie in the coupling of these two models by way of an incremental approach to their representation for different types of scattering particles. A first step can be the modeling of concrete composition by elastic inclusions in a cement matrix with the GSCM model to obtain an equivalent homogeneous medium. Then this equivalent medium can be used like a matrix for the second step, including spherical cavities with the WT model to take into account damage in concrete. Thus, with these two steps, one can reach a high volume fraction of obstacles in the elastic matrix. This outcome allows the use of these models to be validated in media with a very high scattering particles volume fraction for the prediction of phase velocity and attenuation but neglecting multiple scattering effects between the two types of scatterers. Another way to improve ultrasonic nondestructive characterization of heterogeneous media with high particle concentration can be conducted using a model which integrates mode conversion.
An experimental evaluation of two effective medium theories for ultrasonic wave propagation in concrete
Chaix, Jean-Francois (Autor:in) / Rossat, Matthieu (Autor:in) / Garnier, Vincent (Autor:in) / Corneloup, Gilles (Autor:in)
Journal of the Acoustical Society of America ; 131 ; 4481-4490
2012
10 Seiten, 12 Bilder, 2 Tabellen, 30 Quellen
Aufsatz (Zeitschrift)
Englisch
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