Vol 3 - Issue 1

Uncertainties and Reliability of Multiphysical Systems

List of Articles

The purpose of this paper is to perform modal analysis of truss by finite element method. The truss studied has 13 degrees of freedom, which led to mass matrix and stiffness tedious. The Matlab computer tool made it possible to carry out the matrix calculation and to realize the graphical representation of the displacement of the nodes of the truss for each mode of vibration. This representation illustrates the modal deformation of the truss.

The classical topology optimization leads to a prediction of the structural type and overall layout configuration, and gives a rough shape description of the outer as well as inner boundaries of the structure. While, the Reliability-Based Topology Optimization (RBTO) model leads to several reliability-based topologies with high performance levels. Several strategies have been developed in this area considering two points of view: topology optimization and reliability analysis. In this work, a literature review of this different developments considering the two points of view over the last 20 years is presented to show that the different developments considering the point of view ’topology optimization’ generate several reliability-based topologies, however, the other developments considering the point of view ’reliability analysis’ lead to a single configuration. A numerical application on fatigue damage analysis is considered as a validation of the developed methods taking the point of view ’topology optimization’ into account.

Mechatronics is a discipline that combines mechanics, electronics and computer science. The
appearance of mechatronic systems gives rise to failure and degradation phenomena that develop over time and are not well controlled. To study these failures we will use the finite element method, is a numerical scheme (method) that allows to simulate (solve) complicated physics problems via the computer tool. This is made by approximating the mathematical model based on a partial differential equation whose number of unknowns is infinite with a matrix algebraic model whose number of unknowns is finite. The implementation of this method is made with two software programs COMSOL and ANSYS, and the simulations will allow us to observe the behavior of our component and detect the origin of the failures.

L’éolienne à axe horizontal (HAWT) est l’une des architectures les plus diffusées parmi les systèmes traditionnels de conversion d’énergie éolienne, en raison de sa grande efficacité aérodynamique. Plusieurs travaux sur les éoliennes portent sur les différents aspects de la dynamique des fluides de la pale du rotor, afin d’améliorer son efficacité et, par conséquent, la production globale d’énergie. Dans cet article, une simulation numérique a été réalisée en tenant compte de la déformation due à la charge aérodynamique d’une pale d’éolienne en effectuant une analyse d’Interaction Fluide-Structure (IFS) en régime permanent en développant une charge aérodynamique sur cette pale sous ANSYS/Fluent. Ensuite, les pressions sur les interfaces de la pale sont transmises sous forme de charges de pression à ANSYS/Mechanical pour déterminer les contraintes et déformations de la pale. La pale mesure 43,2 m de long et commence avec une forme cylindrique à la racine, puis passe aux profils S818, S825 et S826 pour la racine, le corps et la pointe, respectivement. Cette pale a également un pas variable en fonction du rayon, ce qui lui donne ainsi une torsion et l’angle de pas à l’extrémité de la pale est de 4°. La pale est faite d’un matériau composite orthotrope, elle a une épaisseur variable et possède également un longeron à l’intérieur pour la rigidité structurelle. Le vent turbulent s’écoule à 12 m/s, ce qui est une vitesse de vent nominale typique pour une éolienne de cette taille. Ce flux entrant est supposé faire tourner la pale à une vitesse angulaire de -2,22 rad/s autour de l’axe z. L’écoulement sera simulé autour d’une seule pale et la solution sera extrapolée aux deux autres pales afin de visualiser les résultats pour un rotor à 3 pales.

The objective of this study is to show that composite materials based on plastic reinforced with mineral fibers (glass or carbon, etc.) used in structural parts of the automobile, assembled with their environment via bolted connections, are able to replace some steel parts. While keeping these materials have industrial and economic advantages; as they permit on the one hand to lighten the automotive structure for less consumption of fuels and on the other hand to lower the cost of manufacture for more competitiveness in the automotive market. The tasks that have been done in this study is to submit these composite parts to the same stresses as steel, by using new concepts so that they adapt to their environment and reply to the criteria of reliability and validation’s car approval. The results of numerical simulations show the ability of these materials to replace steel in structural parts of the automobile and they represent a strategic choice in the automotive industry of the future.

Aerodynamics is defined as the science of handling a fluid that is often the air interacting with a structure. In this science, the number of searches is increasing and growing rapidly due to the rapid evolution of Computational Fluid Dynamics (CFD) that has been driven by the need of faster and more accurate methods. The mesh, in these numerical simulations, plays a preponderant role because it makes it possible to discretize the system of equations to be solved and thus to represent the geometry studied. However, there are many problems for which it is advantageous to solve the equations in a moving frame. The Dynamic Mesh (DM) model is used to model flows in which the shape of the domain changes over time due to movement on the boundaries of the domain. In this paper, this technique of the moving mesh was presented and applied for the simulation of a two-dimensional transonic flow over a NACA0012 airfoil using ANSYS/Fluent, validated with the provided experimental data, and the results of this technique are then compared. The flow to be considered is compressible and turbulent and the solver used is the density based implicit solver, which gives good results for high speed compressible flows.