Note sur la propagation des vagues en zone de surf interne

In this paper we present a theoretical study on wave propagation in the inner surf zone. We analyze wave distortion and dissipation processes from the hyperbolic theory for shock wave applied to Saint-Venant equations. From this theoretical approach we obtain an analytical model for broken waves propagation on a gently sloping bottom. We show that there is a very good agreement between this model and wave flume experiments performed by Stive (1984).     

Influence du polymorphisme sur les propriétés mecaniques de quelques polyoléfines

Sans résuméAvec 9 figures and 3 tableaux     

Effet d'un champ magnétique transversal sur la stabilité de l'écoulement de Hartmann : les modes tridimensionnels

A numerical study is conducted in order to determine the influence of a transverse magnetic field on the three-dimensional instabilities of the Hartmann flow. We prove that the Squire transformation currently used to characterize such instabilities give satisfactory results only in the case where Ha is weak and 3D modes are slightly deviated from the 2D modes. Such a study is justified by the fact that the two-dimensional instabilities could not always explain successfully the experimental observations relating to the transition phenomenon. To cite this article: M. Jédidi et al., C. R. Mecanique 333 (2005).     

Modélisation probabiliste d'une expérience ultrasonore : calcul de la dispersion sur les mesures de célérité

This Note presents a probabilistic model of transient wave reflection at a fluid–solid interface. The configuration represents an ultrasonic experiment used for bone tissue evaluation. The parametric method is used to derive the probabilistic model for the mechanical parameters of the solid (bone); the associated random variables are derived according to the maximum entropy principle. A Monte Carlo simulation, associated with the Cagniard–de Hoop method to calculate the acoustic response, yields the probability density for an output ultrasonic parameter similar to the velocity of longitudinal waves in the solid. Results demonstrate the sensitivity of the probability density of this parameter to the experimental setup. To cite this article: K. Macocco et al., C. R. Mecanique 333 (2005).     

Une nouvelle technique de détection des endommagements dans les composites basée sur l'utilisation des micro-ondes et des circuits microrubans résonants

In this article, we present an innovative non-destructive method of detecting damage in composite materials. The method is based on the observation and analysis of the modifications in a material's dielectric properties that result from damage. The originality of this method comes from the fact that the diagnostic is obtained by using a microstrip resonator submitted to a microwave electromagnetic field. In this Note, the method's feasibility is demonstrated by the detection of fibre ruptures in a unidirectional composite submitted to flexural loading. To cite this article: J. Rossignol, A. Thionnet, C. R. Mecanique 334 (2006).     

On the impact of anisotropy on dispersion spectra of acoustic waves in platesImpact de l'anisotropie sur les spectres de dispersion des ondes élastiques dans des plaques

A brief overview is given of specific features that can (or cannot) appear in the dispersion spectra of traction-free elastic homogeneous plates due to anisotropy. Its effect on the overall spectral configuration and on the short and long wave trends is illuminated with a link to anisotropic traits of bulk and surface waves. Relevant classical and recent results are put together, and new points are established. To cite this article: A.L. Shuvalov, C. R. Mecanique 334 (2006).     

Composites graphite/sel pour le stockage d'énergie à haute température : étude des effets du graphite et de la microstructure des composites sur les propriétés de changement de phase des sels

Thermal energy storage at high temperature is an efficient way for energy saving in the industrial sector, as well as a key component for power generation based on renewable energy resources. Thermal energy storage technology based on phase change materials (mainly salts) has been identified to meet the requirements of investment costs and compactness. However, the low thermal conductivity of salts (1 W/m/K) could be a limiting factor concerning power. To overcome such a drawback, new materials combining salts with graphite have been developed. Nevertheless, it is important to verify that no degradation of the salts storage properties is induced by their thermal conductivity enhancement. In this Note, the effects of the graphite and the composites graphite/salt microstructure on the phase change properties of salts are analysed. To cite this article: J. Lopez et al., C. R. Mecanique 336 (2008).