Nacef Ghodhbani - Academia.edu (original) (raw)
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Universiti Sultan Zainal Abidin, Terengganu, Malaysia
National Technical University of Athens
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Papers by Nacef Ghodhbani
Journal of the Acoustical Society of America, 2016
Journal of the Acoustical Society of America, 2016
La caractérisation expérimentale ultrasonore des propriétés viscoélastiques des matériaux fait ap... more La caractérisation expérimentale ultrasonore des propriétés viscoélastiques des matériaux fait apparaitre une dispersion relative importante. La reproductibilité de l'incidence normale et la sensibilité thermique des propriétés ont été identifiés comme des paramètres prépondérants. Leur impact est étudié dans la perspective d'une application sur un suivi de fabrication de plaques composites par le procédé RTM. Afin d'évaluer la sensibilité de la caractérisation à ces phénomènes perturbateurs, les paramètres ultrasonores que constituent l'atténuation et la vitesse de phase ont été mesurés à température ambiante pour deux références d'huiles silicones 47V50 et 47V350 (Rhodorsil ®). Plusieurs méthodes et variantes de caractérisation ont été mises en oeuvre : temps de vol, inter-corrélation et méthode spectrale. Ainsi, les paramètres ultrasonores sont présentés après avoir été corrigés en lien avec la sensibilité des mesures à la température ambiante. La dispersion e...
Ultrasonics, 2015
The perturbation factors involved in ultrasonic broadband characterization of viscous fluids are ... more The perturbation factors involved in ultrasonic broadband characterization of viscous fluids are analyzed. Precisely, the normal incidence error and the thermal sensitivity of the properties have been identified as dominant parameters. Thus, the sensitivity of the ultrasonic parameters of attenuation and phase velocity were measured at room temperature in the MHz frequency range for two reference silicone oils, namely 47V50 and 47V350 (Rhodorsil). Several methods of characterization were carried out: time of flight, crosscorrelation and spectral method. These ultrasonic parameters are measured at room temperature. For this family of silicone oil, the dispersion of the attenuation spectrum is modeled by a power law. The velocity dispersion is modeled by two dispersion models: the quasi-local and the temporal causal. The impact of the experimental reproducibility of the phase velocity and acoustic attenuation was measured in the MHz frequency range, using a set of ultrasonic transducers with different center frequencies. These measurements are used to identify the dispersion of the ultrasonic parameters as a function of the frequency.
An experimental setup has been developed for the monitoring of ultrasonic parameters during polym... more An experimental setup has been developed for the monitoring of ultrasonic parameters during polymerization in the context of the monitoring of composite plate production. An analytical approach is proposed based on the modeling of the wave velocity fitted by a Weibull distribution and was investigated to validate this approach by the Debye series modeling (DSM).The monitoring of the cured epoxy is also performed after curing in order to study the thermal transformation compared with DSC measurements. As a result, an approximated frequency-temperature (f, T) model is proposed for attenuation and velocity frequency and temperature dispersions.
Journal of the Acoustical Society of America, 2016
Journal of the Acoustical Society of America, 2016
La caractérisation expérimentale ultrasonore des propriétés viscoélastiques des matériaux fait ap... more La caractérisation expérimentale ultrasonore des propriétés viscoélastiques des matériaux fait apparaitre une dispersion relative importante. La reproductibilité de l'incidence normale et la sensibilité thermique des propriétés ont été identifiés comme des paramètres prépondérants. Leur impact est étudié dans la perspective d'une application sur un suivi de fabrication de plaques composites par le procédé RTM. Afin d'évaluer la sensibilité de la caractérisation à ces phénomènes perturbateurs, les paramètres ultrasonores que constituent l'atténuation et la vitesse de phase ont été mesurés à température ambiante pour deux références d'huiles silicones 47V50 et 47V350 (Rhodorsil ®). Plusieurs méthodes et variantes de caractérisation ont été mises en oeuvre : temps de vol, inter-corrélation et méthode spectrale. Ainsi, les paramètres ultrasonores sont présentés après avoir été corrigés en lien avec la sensibilité des mesures à la température ambiante. La dispersion e...
Ultrasonics, 2015
The perturbation factors involved in ultrasonic broadband characterization of viscous fluids are ... more The perturbation factors involved in ultrasonic broadband characterization of viscous fluids are analyzed. Precisely, the normal incidence error and the thermal sensitivity of the properties have been identified as dominant parameters. Thus, the sensitivity of the ultrasonic parameters of attenuation and phase velocity were measured at room temperature in the MHz frequency range for two reference silicone oils, namely 47V50 and 47V350 (Rhodorsil). Several methods of characterization were carried out: time of flight, crosscorrelation and spectral method. These ultrasonic parameters are measured at room temperature. For this family of silicone oil, the dispersion of the attenuation spectrum is modeled by a power law. The velocity dispersion is modeled by two dispersion models: the quasi-local and the temporal causal. The impact of the experimental reproducibility of the phase velocity and acoustic attenuation was measured in the MHz frequency range, using a set of ultrasonic transducers with different center frequencies. These measurements are used to identify the dispersion of the ultrasonic parameters as a function of the frequency.
An experimental setup has been developed for the monitoring of ultrasonic parameters during polym... more An experimental setup has been developed for the monitoring of ultrasonic parameters during polymerization in the context of the monitoring of composite plate production. An analytical approach is proposed based on the modeling of the wave velocity fitted by a Weibull distribution and was investigated to validate this approach by the Debye series modeling (DSM).The monitoring of the cured epoxy is also performed after curing in order to study the thermal transformation compared with DSC measurements. As a result, an approximated frequency-temperature (f, T) model is proposed for attenuation and velocity frequency and temperature dispersions.