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International audience; In this work, a thick-walled spherical vessel made of nonhomogeneous materials subjected to internal and/or external pressure was analyzed within the context of three-dimensional elasticity theory. A closed-form analytical solution was obtained for computing the displacement and stress fields. It has been assumed that the elastic stiffness is varying through thickness of the functionally graded material according to a nonlinear general expression, while Poisson’s ratio is considered as constant. In order to check the relevance of the analytical solution, a finite element model of the pressurized vessel were constructed, taking into account variations in Young's modulus. Very good agreement has been found between the numerical results and the predictions of the analytical solution, which confirms the accuracy of our model. Thus, the inhomogeneity in material properties can be exploited to optimize the distribution of displacement and stress fields.

In this paper, an analytical solution is presented for computing mechanical displacements and stresses in a thick-walled cylindrical pressurized vessel made of functionally graded materials (FGM). The pressure vessel is subject to axisymmetric mechanical loading within a uniform magnetic field. The analytical model of the pressurized vessel was constructed, where the radial continuous varying of elastic modulus and permeability along the thickness was assumed. It has been assumed that the elastic modulus and permeability are varying through thickness of the FG material according to a nonlinear general distribution along the thickness. Navier’s equation, which is a second-order ordinary differential equation, was derived from the mechanical equilibrium equation with the consideration of the Lorentz force resulting from the magnetic field. The distributions of the displacement and stresses were determined by the exact solution to Navier’s equation. Numerical results clarify the influence of the magnetic field, non-homogeneity parameter and internal pressure on the magneto-elastic response of the functionally graded cylindrical vessel. Thus, these parameters have remarkable effects on the distributions of radial displacement and radial and circumferential stresses.

In this paper, analytical and numerical solutions are presented for computing mechanical displacements and stresses in a thick-walled cylindrical made of functionally graded materials (FGMs) under ...

In this paper, analytical and numerical solutions are presented for computing the displacements and stresses in a FGM thick-walled cylinder under a uniform internal and external pressure. An analytical and a finite element (FE) model of the pressurized vessel were constructed, where the radial continuous varying of elastic modulus along the thickness was assumed and implemented in a FE code. It has been assumed that the elastic modulus is varying through thickness of the FGM material according to a nonlinear general expression. The analytical solutions of distribution of displacements and stresses were obtained and illustrated in radial direction for pressurized FGM cylinder. The results are checked with FE results. Thus, the inhomogeneity in material properties can be exploited to optimize stress distribution.

In the present paper, a study of the weak shock waves propagation into thermohyperelastic solids is presented using the theory of singular surfaces. The equation of motion of the weak shock waves, which is obtained by the later theory, reduces to an eigenvalue problem. The propagation speeds of weak shock waves are obtained from the eigenvalues of the isentropic acoustic tensor for a particular state of deformation. The constitutive equation of a near-incompressible thermohyperelastic solid is considered. This constitutive model derives from a Helmholtz free energy which does not seem to be used in published scientific literature. The shock waves speeds are expressed in the framework of standard loadings: simple uniaxial tension, biaxial stretching, and uniform dilatation. The material seems to be always stable, and no singularity of the isentropic acoustic tensor has been found which corresponds to a critical state.

The purpose of this paper is to investigate rheology and hydrodynamic behavior of different mass concentration of bentonite suspensions in pipe flow. Bentonite suspensions exhibited shear thinning and yield stress non-Newtonian rheological behavior. Most of the data reported are for the laminar and turbulent flow, data are also included the start-up flow development. The axial velocity distribution was determined using a Ultrasonic Pulsed Doppler Velocimetry technique. The experimental results show a progressive destructuration of the suspensions in the entrance region due to the segregation of the structural elements of the fluid and tend to a steady state and a fully developed laminar pipe flow. In the majority of cases, axisymmetric flow is observed for both laminar and turbulent flow conditions. Also an asymmetry characterizes the axial velocity profiles in the laminar-turbulent transitional flow. In the laminar regime, the flow parameters were fitted by using the Herschel–Bulkley model. For the turbulent flow, the Dodge and Metzner model was applied to fit the experimental data.

L’objectif de notre travail est d’apporter un supplement de connaissance quant au comportement mecanique des boues biologiques en ecoulement. Pour ce faire, des fluides modeles ont ete mis en oeuvre. Il s’agit notamment de suspensions d’argile et de melange argile-polymere. Les fluides utilises sont une suspension de bentonite de concentration massique de 5 % et un melange de 5 %/0.1 % bentonite/carboxymethyl cellulose de sodium (CMC). Il a ete etabli que le comportement rheologique de l’argile et du melange peut etre caracterise par un modele a trois parametres de type Herschel-Bulkley. Un accent est mis sur l’effet de l’ajout de polymere sur les proprietes rheologiques et en ecoulement des boues. Cette etude est motivee, d’une part, par le fait que le polymere est un constituant de la boue elle-meme et d’autre part, par son utilisation comme additif pour le controle des proprietes physiques des boues. En regime laminaire les parametres d’ecoulement sont en accord avec les resultats analytiques obtenus a partir du modele de Herschel-Bulkley. En regime turbulent, les equations de Dodge et Metzner modelisent de maniere satisfaisante le comportement de ces fluides. Il a ete montre que le polymere a des proprietes viscosifiantes en regime laminaire, par contre en regime turbulent, il est un reducteur de frottement.

L’objectif de notre travail est d’apporter un supplement de connaissance quant au comportement mecanique des boues biologiques en ecoulement. Pour ce faire, des fluides modeles ont ete mis en œuvre. Il s’agit notamment de suspensions de bentonite. A partir des mesures de profils de vitesses et des pressions, notre etude experimentale porte sur l’etude de l’evolution des parametres rheologiques des boues en ecoulement dans une conduite rectiligne. Nous etudions les profils de vitesse. Ces derniers sont caracterises par une zone bouchon au cœur de l’ecoulement et une zone cisaillee a la paroi. L’effet des singularites sur la destructuration des suspensions a ete mis en evidence. La mesure des viscosites montre le caractere rheofluidifiant des boues. L’etude des coefficients de frottement montre une evolution inversement proportionnelle au nombre de Reynolds en regime laminaire ainsi qu’une transition a la turbulence a partir de Re exp = 2050.