Advanced Materials Research Vol. 682

Abstract: The comprehension of the interactions between a fluid and an elastic solid has a capital importance in several industrial applications. When a structure vibrates in the presence of a fluid, there is interaction between the natural waves of each media: the fluid flow generates a structural deformation and/or the movement of a solid causes the displacement of the fluid. These applications require an effective coupling. In addition, the dynamic analysis of the industrial systems is often expensive from the numerical point of view. For the coupling fluid-structure finite elements models, the importance of the size reduction becomes obvious because the fluid's freedom degrees will be added to those of the structure. A method of condensation will be used to reduce the matrixes size. One of the principal hypothesis in the use of component mode synthesis method is that the model is deterministic; it is to say that parameters used in the model have a defined and fixed values. Furthermore, the knowledge of variation response of a structure involving uncertain materials, geometrical parameters, boundary conditions, tolerances of manufactures and loading conditions is essential in global process of conception. In order to do that, the modal condensation method is extended to reliability analysis for the coupled fluid-structure finite elements models. A numerical vibratory study is leaded on a plate in the air and in immersion in water taking into account the acoustic aspect. The results of the reliability analysis tend to show the effectiveness of the proposed approach based on the condensation techniques.

Abstract: This paper is based on the study of acoustic scattering classic RST, in which it was introduced the method of MRST (multichannel resonant scattering theory) to study the problem of interaction of acoustic waves normal incidence in environments consisting of a biphasic isotropic elastic matrix in which is inserted a fluid inclusion (cylindrical or spherical). Initially we implement the transition matrix S containing the mode n of the longitudinal (L) and transverse (T) of the wave in the elastic medium. The isolation of resonances characteristic of the fluid inclusion is done via the S-matrix factorization as a product of the matrix of soft bottoms no resonant matrix and resonances. To improve the localization of the resonances we undertake a study of the absolute phase in connection with MRST. A numerical simulation of cavity fluid (water) cylindrical and spherical copper in a matrix, showed the effectiveness of the absolute phase spectra for the exact determination of the resonances.

Abstract: This paper presents a numerical procedure to compute the robustness function of large finite element models with parameter uncertainties based on convex models and component mode synthesis methods (CMS). For an optimal reduction of the size of the model the CMS with reduction of interface dof is used. This coupling methodological approach is used on one hand to reduce the size of the model and on the other hand to analyze the structures where the data on the uncertainties are limited enough. Robustness function is determined and the dynamic analysis of large and composed structures is investigated. Numerical results illustrating the efficiency of the proposed coupled procedures for large FE models with random parameters are presented.

Abstract: The mechanical response of the composite structure in T650-35/PMR-15 aged at different temperatures was studied numerically. The time-dependent internal stresses in the composite ply and its constituents were computed during the creep process. In order to predict the effective properties of PMR-15/T650-35 composite ply in the temperature range [250-350°, the time-dependent mechanical properties of PMR-15 matrix determined experimentally [, were considered. The mechanical properties of the fibers do not experience any change due to the aging process in such a temperature range [2, . In order to achieve the computations, the visco-elastic Eshelby Kröner self-consistent model was used.

Abstract: The bucket is a metal entity, linked to a machine called DRAGLINE, used for loading the different sizes of granular materials in large quantities. Each bucket is provided with six teeth which in contact with materials to be discharged, in order to extract the mineral. These teeth are connected to the bucket via a semi-rigid connection. In operation, except for the wear phenomenon "normal", some teeth break after a few hours of operation at the fixed portion in the singularity region (radius of curvature equal to zero). We observed via elastic numerical simulation in quasi-static regime, performed using PATRAN and NASTRAN software, that hot spots are located at the singularity region. We also used this numerical calculation for analyzing the effect of the variation radius of curvature on the stress concentration factor by plotting the variation of this factor vs of said radius. To deepen, we repeated the same study but this time considering the material of the tooth as elastic perfectly plastic for seeking the limit load. For each value of the radius of curvature, was plotted the variation of the elasto-plastic external force according to the displacement of the front end of the tooth, knowing that the other end is fixed.

Abstract: The use of multi-layered composite materials in the confection of industrial pipe connections (elbows, reduction pipes, flanges etc.) is often put off because of the high cost of manufacture. The aim of this study is to replace the multi-layer process (woven reinforcement-organic matrix) by sandwich process with a view to reducing the cost of manufacture. Validation is carried out on different structures: ring, cylinder with and without end effect, elbows and floating flanges.

Abstract: Analytical solutions are derived for multifunctional N-layered rectangular plates. The multilayered plate may consist of linear elastic or piezoelectric laminates of arbitrary thickness. The related equations and formulae are developed based on the Stroh like formalism. Solutions for multilayered plates are expressed in terms of the propagator matrix and satisfy the continuity conditions of material layers. Various types of electrical and mechanical loading may be considered. Numerical results of stresses, electric potential and displacement for some multifunctional multilayered plates are analyzed

Abstract: Simulations of Single Point Incremental Forming generally require a very high computation time because the tool path is long and small elements are required everywhere on the sheet. In this paper, a remeshing method based on refinement and coarsening strategies is used with abaqus/explicit to reduce the computational time. The simulation of a semi-spherical cup with a fine mesh is considered as a reference simulation. The remeshing method allows reducing the number of elements and therefore the CPU time during the simulations. A good prediction is observed with the remeshing method.

Abstract: Embedded electronic systems are playing a very important role in several areas, such as in automotive, aerospace, telecommunications and medical sectors. To properly perform their functions, electronic systems must be reliable [2. So in this paper, we present a new hybrid method of optimization by the heuristics algorithms to evaluate the reliability of the electronic card by simulating its thermo-mechanical behavior. A model of simulation by finite element is developed to consider the maximal deformations due to the temperature; a mechanico-computing coupling is used to find the optimal structure. This powerful and robust algorithm which is based on hybridation of Genetic algorithm with Particle swarm optimization PSO gives performance results.

Abstract: The dynamic instability analysis of conveying fluid multi-walled carbon nanotubes (MWCNT) is analyzed. Based on the nonlocal elasticity theory, Donnells shell model, potential flow theory and the van der Waal interaction between walls, the governing equations are formulated. The small scale parameter and the internal fluid interaction effects on the dynamic behaviors of the MWCNT-fluid system as well as the instabilities induced by the fluid velocity are investigated. The critical velocity and the frequency-amplitude relationships are obtained with respect to physical and material parameters.