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Über dieses Buch

This book reports on the state of the art in the field of multiphysics systems. It consists of accurately reviewed contributions to the MMSSD’2014 conference, which was held from December 17 to 19, 2004 in Hammamet, Tunisia. The different chapters, covering new theories, methods and a number of case studies, provide readers with an up-to-date picture of multiphysics modeling and simulation. They highlight the role played by high-performance computing and newly available software in promoting the study of multiphysics coupling effects, and show how these technologies can be practically implemented to bring about significant improvements in the field of design, control and monitoring of machines. In addition to providing a detailed description of the methods and their applications, the book also identifies new research issues, challenges and opportunities, thus providing researchers and practitioners with both technical information to support their daily work and a new source of inspiration for their future research.

Inhaltsverzeichnis

Frontmatter

Influence of the Plies Orientation on the Rigidity of the Laminated Composites

The overall properties of a laminated composite structure depend on design thereof, i.e., they depend on the thickness, on the orientation and the material of each ply in the stacking sequence, that is why optimization tools are used to assist decision making and designing structures with optimized properties. In this study, the design variables are only the plies orientation because the plies number, the material and the thickness are already selected. This problem will be treated as an optimization problem under constraints, whose objective function is the modulus of transverse stiffness of laminated composite to maximize, and the optimization variables are the plies orientation. The Monte Carlo method is applied as a constrained stochastic optimization, based on stratification parameters for the determination of optimal fiber orientations laminate structures to find the maximum longitudinal modulus of rigidity (E

x

). Validation results of this approach have been compared with the results of Girard [4] who has used a genetic algorithm to optimize laminates by using equations of the classical theory of laminates and, by referring to the results of Luersen [3].

Abdelghani Belkadi, Ali Ahmed Benyahia, Nourdine Ouali

Simplified Calculation Methods on Smoke and Temperature Stratification in Ventilated Compartments

Using different calculation methods with respect to smoke and heat evacuation systems (SHEVS), a comparative study is presented with regards to enclosure fire in large single storey compartments. A focus is made on European and American manual methods for which a set of graphical Matlab routines are developed. The results obtained with several modeling approaches are discussed in this paper.

Souhila Agred, Abdallah Benarous, Djamel Karmed, Larbi Loukarfi

Analysis of the Notched Specimens on the Fracture Behavior by the Volumetric Method

A single edge notched specimen is commonly used in materials of steel construction for the determination the notch stress intensity factor. CT- specimen is considered as a finite element model containing an elliptical notch under a uniform uni-axial tensile loading. The volumetric method is applied in perfect elastic-plastic behavior. Changing made to notch parameters influences the evaluation of the effective stress accordingly the results of the notch stress intensity factor.

Mustafa Moussaoui, Salim Meziani

Temperature Effect on Shear Flow and Time Dependant Modelling of Cutting Oil Emulsion

The effect of temperature and shear rate on rheological behaviour of cutting oil emulsion was investigated in this work. The model of Herschel-Bulkley was used to fit the shear stress dependence of the shear rate for temperatures between 20°C and 100°C. The temperature increase induced not only a decrease in the yield stress and the consistency index of cutting oil emulsion but also an increase of the flow index of cutting oil emulsion. The temperature dependence of limit viscosity at high shear rate of the cutting oil emulsion was fitted by an Arrhenius equation. For constant shear rate applied on the cutting oil emulsion at 20°C a thixotropic behaviour was observed and analysed using a modified model of Herschel-Bulkley in which a structural parameter

λ

was included in order to account for time dependent effect.

Larbi Hammadi, Nasr-Eddine Boudjenane, Mansour Belhadri

A Comparison between Two Reliability Based Optimization Strategies of Tuned Mass Damper Parameters under Stochastic Loading

In this work two reliability based optimization (RBO) strategies of Tuned Mass Damper (TMD) parameters are presented and compared. The TMD device is attached on a primary structure modeled by a generic one degree of freedom system. The first strategy is based on the displacement response of a primary structure whereas the second one is based on a new approach related to the dissipated power (DPO). Analytic expressions of the failure probabilities are given based on the Rice’s formula. The obtained results proved that both strategies are earthquake dependant for earthquake frequency close to the main system frequency. A correlation analysis is made and it has been found that the new RBO strategy is more robust in the sense that it can provide the result of the displacement RBO with a small relative error.

Elyes Mrabet, Mohamed Guedri, Samir Ghanmi, Mohamed Soula, Mohamed Ichchou

Modeling and Simulation for Vertical Rail Vehicle Dynamic Vibration with Comfort Evaluation

Investigation of vibration is an important topic for the purposes of ride comfort in railway engineering. The vibration of rail vehicles becomes very complex because it is affected by the condition of vehicles, including suspensions and wheel profile, condition of track sections, including rail profile, rail irregularities, cant and curvature. The present study deals with the effects of railway track imperfections on dynamic behavior, and investigates the effect of vehicle speed and the rail irregularity on ride comfort through numerical simulation. The numerical simulation of the vertical dynamic behavior of a typical railroad vehicle will be performed using Largrangian dynamics. The model consists of 17 degrees of freedom with 4 wheelsets, 2 bogies and a car body. For the assessment of the ride comfort, the Sperling ride index (ISO2631) is calculated using filtered RMS accelerations. The ride characteristics of the vehicle provide an assessment of the dynamic behavior of the vehicle through the analysis of the accelerations at the vehicle body, whereas the ride comfort assesses the influence of the vehicle dynamic behavior on the human body. A parametric study was carried out to suggest design modifications in order to improve the level Sperling index.

Mortadha Graa, Mohamed Nejlaoui, Ajmi Houidi, Zouhaier Affi, Lotfi Romdhane

Localization of Impact on a Beam by Time Reversal Method

This paper deals with a numerical simulation of time reversal (TR) process applied to a cantilever beam. To conduct this process we assume a finite difference scheme based on Euler-Bernoulli theory of transversal vibration of the beam. The TR process is then used to localize the position of an impact on the beam. To complete the TR process we need one or more measurements of the field on different positions. We had study the effect of the measurements number and their positions on the localization with the TR process. The objective of this study is to reduce the number of measurements and hopefully use it in an experiment with few measuring instruments.

Omar Chaterbache, Abdelhamid Miloudi

Early Detection of Gear Failure by Vibration Analysis

Gear mechanisms are an important element in a variety of mechanical systems, such as industrial machinery and automotive. Health monitoring of rotating machines is important to avoid failure of the system in advance. Principally, this paper consists of two parts: in the first part, a gear dynamic model including localized tooth defect has been developed. The model consists of a spur gear pair, two inertias. The model incorporates the effects of time-varying mesh stiffness and damping, excitation due to gear errors. The results of a dynamic modeling of the gears transmission are calculated by using the Newmark integration scheme. The second part consists of signal processing of simulated and experimental signals using the wavelet transform. It is shown that the kurtosis of the vibration signal is a sensitive indicator of the existence of damage in the gear pair.

Mustapha Merzoug, Khalid Ait-Sghir, Abdelhamid Miloudi, Jean Paul Dron, Fabrice Bolaers

Effect of Water Hammer in Relatively Long Inclined Pipelines

Consideration is given in this paper to the numerical solution of transient flows in relatively long pipeline provoked by the water hammer phenomenon. Equations which describe these one-dimensional flows in a cylindrical pipe, of linear elastic behavior according to the Hooke’s law, are solved in the time domain by the method of characteristics using linear integration. The obtained results due to a rapid closure valve at the downstream end of a long pipeline show that the gravity lift may have an important effect on the maximum pressures, which may become very important near the valve and provoke the failure of the pipe especially in presence of defect. The safety factor, computed at equidistant sections of the pipe, determines the distance between the supplying reservoir and the defect from which the failure may happen.

Manel Dalleli, Ezzeddine Hadj-Taïeb, Christian Schmitt, Zitouni Azari

Experimental Study of the 60° PBT6 Pitching Blade Effect with a PIV Application

The aim of this paper is to study experimentally by particle image velocimetry system (PIV) the effect of the pumping direction introduced with a 60° pitched blade turbine. In fact, an Up- and a down-pitched blades turbine were used. The particle image velocimetry technique is equipped with a double pulsed Nd:YAG laser, a CCD camera resolution and a mini-synchronizer. Therefore, several results were carried out to investigate the hydrodynamic structure and the energetic parameters in a stirred vessel.

Bilel Ben Amira, Zied Driss, Mohamed Salah Abid

Incidence Angle Effect on the Aerodynamic Structure of an Incurved Savonius Wind Rotor

In this paper, a computational fluid dynamics investigation has been developed to study the incidence angle effect on the aerodynamic structure of an incurved Savonius wind rotor. The software "SolidWorks Flow Simulation" has been used to present the local characteristics. The numerical model considered is based on the resolution of the Navier-Stokes equations in conjunction with the standard k-

ε

turbulence model. These equations were solved by a finite volume discretization method. An experimental validation has been done using a wind tunnel to confirm the computer method validity.

Zied Driss, Olfa Mlayeh, Dorra Driss, Makram Maaloul, Mohamed Salah Abid

Experimental Characterization of a NACA2415 Airfoil Wind Turbine

In this paper, an experimental characterization of a horizontal axis NACA2415 airfoil type wind turbine has been developed. Particularly, a detailed description of the used wind tunnel and the various manipulations performed are presented to study the aerodynamic characteristics of the wind turbine. The experimental setup is developed to estimate the velocity profiles and the torque meter variation for different Reynolds numbers and wedging angles of the blade. The main objective is to develop results to validate the numerical results established with Computational Fluid Dynamics (CFD) codes.

Zied Driss, Tarek Chelbi, Ahmed Kaffel, Mohamed Salah Abid

DFMM Approach: Modelling, Formalization and Choice of Material and Manufacturing Processes

In a very competitive industrial world, the integrated design and particularly the design for manufacturing make progress the profitability of the product. The DFM (design for manufacturing) improves the transition between the design and the manufacturing phases and reduces the time and the costs of product manufacturing. Within this framework of research, the DFMM approach (design for material and manufacturing) takes into account the constraints of manufacturing, as of the phase of design, and makes it possible to choose consequently the most adequate material and processes for the manufacturing of the mechanical parts. This approach is composed primarily of the modelling of the product, the manufacturing knowledge management, the choice of material and the choice of manufacturing processes.

Mohamed Saidi, Achraf Skander, Slim Kaddeche

Study of the Aerodynamic Structure around an Obstacle with Inclined Roof

In this work, we are interested on the study of the aerodynamic structure around an obstacle with inclined roof for a Reynolds numbers equal to Re=2666. The software “SolidWorks Flow Simulation” has been used to present the local characteristics. The numerical model considered is based on the resolution of the Navier-Stokes equations in conjunction with the standard k-

ε

turbulence model. These equations were solved by a finite volume discretization method. The numerical model is validated with experimental results conducted on an open wind tunnel.

Slah Driss, Zied Driss, Imen Kallel Kammoun

Contribution to Inverse Kinematic Modeling of a Planar Continuum Robot Using a Particle Swarm Optimization

According to the literature, research on modeling continuum robots is focused on ways to develop the kinematic models, because of the lack of analytical models for these robots and the complexity of the problem which reside in the coupling of operational variables and infinite of possible solutions for a desired configuration. This paper presents a numerical approach for solving the inverse kinematic model of a planar continuum robot (PCR), assuming that each section of the manipulator is curved as a circular arc, with an inextensible central axis of the structure. At first, this paper presents an inverse kinematic model solution for one bending section, whereas the extreme points, of each section, used in calculating the inverse kinematic model for multi-sections is calculated numerically using a particle swarm optimization (PSO) technique. Finally, Simulation examples of this method are carried to validate the proposed approach.

Ammar Amouri, Chawki Mahfoudi, Abdelouahab Zaatri

Experimental and Numerical Study of Beams under Low-Velocity Impact

This paper is an experimental and numerical study of the low velocity impact on beams. It is shown that the numerical model adopted, for the impact force history, produces numerical results in good agreement with experimental data. The analysis establishes that the contact point position is insignificant on the main impact and rebounds are closer in time when we approach the clamped edge. The increasing of the incident energy (mass or celerity of the striker) has the effect of amplifying the impact force without changing its duration in the case of the velocity and with increasing the amplitude of the impact force in the case of the mass. However elevated hardness of the contact aggravates the impact effects by increasing the magnitude and decreasing the contact force duration.

Mahmoud Neder, Abdelhamid Miloudi

Modeling of Cutting Forces and Roughness by the Response Surface Method (RSM)

Longitudinal turning results in a cutting force whose decomposition in three preferred directions can be the basis for the definition of cutting forces for all machining operations.

The work presented in this paper aims to modeled phenomena that occur when shooting steel Fk 20 Mn Cr 5 with a metal coated carbide tool P40.

The main objectives focused on the delineation of the area of the shooting and to study the relationship between the cutting parameters (cutting speed, feed and depth of cut) and the response variables cutting forces and roughness of the machined parts through the response surface methodology (RSM). The resulting models are types: quadratic, linear, exponential, Gilbert and genetic algorithm.

Fayçal Bentaleb, Idriss Amara

Analysis of Inelastic Behavior of Amorphous Polymers

A physically constitutive model based on the concepts of quasipoint defects and hierarchically constrained molecular dynamics is applied to describe the sub-Tg inelastic behavior of amorphous polymers over a wide range of temperature and strain rates. Temperature and strain rate greatly influence the mechanical response of amorphous polymers. The results satisfactorily reproduce experimental observations and provide a general physical explanation for the occurrence of the change in deformation regime observed at a temperature lower than Tg. The kinetic equilibrium occurring between the creation of defects due to plastic deformation and their annihilation through structural relaxation is shown to play a major role in the existence of the two regimes of deformation.

Nourdine Ouali, Ali Ahmed Benyahia

First Principal Calculations of Optical Properties of InGaN2 Using in Solar Cells Applications

The aim behind this work is to look into the optical properties of InGaN

2

with chalcopyrite structure in ternaries compounds. To obtain precise results, we have used the first-principles calculations, using the full potential-linearized augmented plane wave method (FP-LAPW) within the density functional theory (DFT). in order to get best and accurate values of the band gap, as exchange–correlation potential, , we have used the modified Becke – Johnson (mBJ) of Tran and Blaha, which are based on the optimization of total energy and corresponding potential. The InGaN

2

chalcopyritedemonstrates semiconducting behavior, with the direct-band gap of 1.68 eV. We have studied the dielectric function, refractive index, reflectivity, absorption coefficient, and the optical conductivity function. The results we have obtained indicate that InGaN

2

is an attractive and promising material for optoelectronic and photovoltaic applications.

Hamza Bennacer, S. Berrah, A. Boukortt, Mohamed Issam Ziane

Agent-Based Approach for the Optimal Design of Mechatronic Systems

Mechatronic design optimization is a hard task especially if performed by several different designers geographically distributed and using different modeling tools. Therefore, the design tasks should be divided into partitions easier to manage to reduce this complexity. However, the optimization of the overall design requires incorporating the relevant partitions in order to find the optimum mechatronic design. Efficient strategies of partitioning and coordination should be specified at the conceptual level to have a successful optimization process. In this study, a new efficient collaborative optimization approach based on multi-agent paradigm is proposed for mechatronic design optimization. The proposed method is applied to the preliminary design case of an electric vehicle to demonstrate its validity and effectiveness.

Amir Guizani, Moncef Hammadi, Jean-Yves Choley, Thierry Soriano, Mohamed Slim Abbes, Mohamed Haddar

A Digital Pattern Approach to the Design of an Automotive Power Window by means of Object-Oriented Modelling

The paper deals with a digital pattern (DP) approach to the design of an automotive power window, using object-oriented modelling. Therefore, the paper faces the designing of a mechatronic system by using an integrated approach to product development. Then, Dymola/Modelica environment is used as a tool of a decision support system that makes possible the DP approach. The paper briefly sum up the results of simulations related to a power window system characterized by a double bowden sliding mechanism. Finally, the paper highlights the parameters that could be easily integrated in a graphical user interface, aimed to reduce both the development time of new power window system and to increase the accuracy of design activities.

Stanislao Patalano, Ferdinando Vitolo, Antonio Lanzotti

Numerical Study of the External Excitation Amplitude Effect on Liquid Sloshing Phenomenon

In this work, we are interested on the study the liquid sloshing phenomena in a tank subjected to a sinusoidal excitation. Particularly, we have investigated the amplitude movement effect. The hydrodynamic parameters describing the flow like the velocity and the static pressure are presented. The numerical results are investigated for four different values of sinusoidal excitation amplitude. The results show that the behavior of the sloshing phenomenon strongly depends on the amplitude value of the external excitation. A good agreement has been shown by comparing the numerical and the experimental results.

Bouabidi Abdallah, Zied Driss, Abid Mohamed Salah

The Study of the Hardening Precipitates and the Kinetic Precipitation. its Influence on the Mechanical Behavior of 2024 and 7075 Aluminum Alloys Used in Aeronautics

The Research about the aluminum alloys has been in progress. Aluminum alloys, in contrast to the pure aluminum have very high mechanical characteristics of substantial resistance. These mechanical performances combined with lightness of the structure there of has a variety of uses especially in the transport sector. The aluminum alloys of the 2000 series (Cu is a main part of addition) and 7000 (Zn is the main part of addition) are essentially aeronautics alloys, hence its strong presence Air in the design of bus where Al 2024 and Al 7075 are the major part (Figure 1).

Both alloys (2024-7075) are hardening structural alloys and not by strain working. Their mechanical properties are of particular microstructure obtained from thermo-mechanical treatments. Among other things, this is a complicated microstructure which is responsible for these mechanical performances. It is interesting to examine the description of this complex phenomenon of the hardening precipitation, including areas of Guinier-Preston (GP Zone) which are very dependent on the alloy’s composition and thermo-mechanical treatments they undergo. The hardening phases (A.Deschamps2001) of 2024 and 7075 aluminum alloys are respectively (Al2Cu - Al2CuMg) and (MgZn2). These phases are obtained by precipitation of the sequence which depends on the proportions of elements alloying elements. An experimental tensile tests companion of these heat treated aluminum alloys (quenching) will allow us to understand the kinetic precipitation and its influence on the mechanical properties (Rp0.2, Rm and A%), dice quenching cool until maturation (T4).

Ahmed Ben Mohamed, Amna Znaidi, Moez Baganna, Rachid Nasri

Multidisciplinary Design Optimization in Small Satellite

Many industrial tools for simulation developed during these last years still have an impact limited on the complex systems design such as satellites, aircrafts, engines or rockets. Whereas the modeling tools of each discipline or subsystems are refined gradually, the total optimization of these systems encounters difficulties of orders at the same time methodological, organizational, data-processing and numerical. Actually and in the best of the cases, the complex systems are optimized by subsystems. Savings of time of design and performances are accessible if one manages to optimize in a collaborative and robust way the unit of the subsystems. The aerospace structures generally require light designs. The goal of these later is to be optimized the force by weight or effectiveness of the design. The satellite structural design developed considerably during the last four decades. Traditionally, the effectiveness was achieved by a combination of various designs and structural materials. Our objective is to build methods and tools for the robust design and multidisciplinary optimization in the small satellites mechanics design, taking into account the aspects related to attitude and orbit control subsystem, thermal control, static, dynamic and thermo-elastic analysis and including the design of mechanical housing for RF systems. Our proposed method is demonstrated through multidisciplinary design optimization application. In this study, the multidisciplinary design optimization in small satellite mechanical design is formulated as optimization of sub problem involving the appropriate selection of a configuration. The different results obtained in this paper show that the multidisciplinary design optimization methods present a large interest in the space design with an aim of having a reliable space system with lower cost.

Abdelmadjid Boudjemai, Abdelmoumen Bacetti, Mohammed Amine Zafrane, Rachida Hocine

Mechanical Vibration Cancellation Using Impact Absorber

The free and forced vibrations of a mechanical system equipped with a ball absorber were studied. The modeling of the impact damping and the problem formulation and resolution were conducted. The effect of the absorber parameters on the vibration attenuation of the primary system was then examined. The absorber parameters considered are: the mass, the stiffness, the damping, the clearance, and the impact velocity. The excitation parameters were also evoked. Physical and mathematical modeling, then numerical simulation led to determine the free and forced responses of the considered system equipped with the impact absorber, for different situations. This helped to identify the absorber favorable parameters, leading to reduce considerably the primary system vibration, and to advance design recommendations.

Kaouther Chehaibi, Charfeddine Mrad, Rachid Nasri

RFLP Approach in the Designing of Power-Trains for Road Electric Vehicles

This paper is focused on the designing process of propulsion systems for road electric vehicles, by means of the RFLP approach for System Engineering. The process starts from the analysis of the main requirements for the vehicle considered, in relation to its specific mission. The vehicle behavior is then simulated on standard driving cycles, evaluating the performance figures of different power-train configurations, under different operative conditions. The presented designing procedure reaches the 3D CAD model of the identified propulsion system, coupled with a specific laboratory test bench, based on an eddy current brake and flywheel for the simulation of the vehicle inertia. The obtained simulation results show the good performance of the power-train in terms of vehicle speed following its reference on driving cycle and vehicle autonomy.

Clemente Capasso, Moncef Hammadi, Stanislao Patalano, Ruixian Renaud, Ottorino Veneri

Mechanical Vibration Elimination Using Friction Absorber

The work consists on studying the vibration reduction of mechanical systems using friction absorber, with and without viscous damping. The aim is to determine the influence of the friction absorber parameters on the mechanical system response. A study using a nonlinear friction force is conducted while varying the absorber parameters, which are: the mass, the stiffness, the friction coefficient, and the damping coefficient. The linearization of the friction force is then considered, and the results are compared. The effect of the primary system damping and the excitation parameters are also examined. The influence evaluation of the friction absorber parameters on the mechanical system vibration leads to conclude on the favorable absorber giving significant vibration decrease, and to advance design recommendations.

Aymen Nasr, Charfeddine Mrad, Rachid Nasri

AC Flashover: An Analysis with Influence of the Pollution, Potential and Electric Field Distribution on High Voltage Insulator

This paper presents a work devoted to the impact study of the pollution severity on the energy level dissipated on high voltage insulator. Pollution of high voltage insulators is a factor of prime importance in the quality and reliability of power transmission. It causes the circumvention of high voltage insulators. However, when it is wet, it causes the dissolution of salts and the formation of an electrolyte layer on the surface of insulators, thus reducing dielectric strength. Pollution generally poses few problems. However, when it is humid, it causes the dissolution of salts and the formation of an electrolytic layer on the insulator surfaces; as a result, it reduces their dielectric rigidity.

The aim of this paper is the experimental study of the flashover process and the distributions of the potential and the electric field pollution carried out under 50 Hz applied voltage on a circular model simulating the 1512 L outdoor insulator largely used by the Algerian company of electricity and gas (SONELGAZ). This circular model is under different surface conductivity and different level of uniform discontinues pollution.

The computer simulations are carried out by using the COMSOL Multiphysics 3.5 software. This program uses the finite element method to solve the partial differential equations that describe the field. Original experimental results made in the laboratory are presented and compared with a real insulator, and simulations presented in this paper are originals.

Hani Benguesmia, Nassima M’Ziou, Ahmed Boubakeur

Evaluation by Wide-Angle X-ray Scattering of the Particle Evolution in Polypropylene Processed by Equal Channel Angular Extrusion

The equal channel angular extrusion (ECAE) is a process used to improve the mechanical properties of materials. Key parameters to achieve this objective are mainly the geometrical dimensions of the extrusion die and the extrusion parameters such as extrusion rate, the back pressure, the applied load, etc…. The characterization by the use of X-ray showed that the sample extruded at 45 mm/min, and which has light and dark bands due to the stick-slip phenomenon polymer, has sheared in the direction of approximately 45° to the extrusion direction. The using of the Fit2d software can locate the families of crystal planes (hkl) of the PP. Observations by X-ray in the direction of flow have shown the existence of three planes (040), (130) and (111). On the other hand, by the observation in the transverse direction revealed the existence of another plane (131).

Ramdane Boulahia, Taoufik Boukharouba, Jean-Michel Gloaguen

A Multi-site Supply Chain Planning Using Multi-stage Stochastic Programming

This study focuses on a multi-product, multi-period, multi-site supply chain planning problem under demand uncertainty. A multi-stage stochastic linear programming model is proposed to maximize the expected profit. The decisions to be made comprise the production amount, the inventory and backorder sizes as well as the quantity of products to be transported between upstream and downstream plants and customers in each period. A numerical example is presented in order to illustrate the effectiveness of the proposed model. Results indicate that the solution of the multi-stage stochastic model outperforms the deterministic and the two-stage stochastic models.

Houssem Felfel, Omar Ayadi, Faouzi Masmoudi

A System Engineering Conception of Multi-objective Optimization for Multi-physics System

At present, a system involves more and more domains and becomes more and more complex. In this paper, a system engineering conception of multi-objective optimization for a multi-physics system is formed. An example of multi-physics system design illustrates the presented approach.

Mian Chen, Omar Hammami

Falling Film in a Heated Micro-channel

The main objective of this work is to study experimentally and numerically a falling film in a micro-channel. The experimental section involves in creating a temperature gradient within the liquid, while monitoring the temperature using an infrared camera. A numerical model is established and solved by a semi-analytical method called the thermal quadrupole method. Finally, we conclude with a comparison between the experiments and the numerical study.

Sabrine Mejri, Olivier Fudym, Jalila Sghaier, Ahmed Bellagi

Interfacial Stresses in FRP-plated RC Beams: Effect of Adherend Shear Deformations

A recently popular method for retrofitting reinforced concrete (RC) beams is to bond fibre reinforced polymer (FRP) plates to their tensile faces. An important failure mode of such plated beams is the debonding of the FRP plates from the concrete due to high level of stress concentration in the adhesive at the ends of the FRP plate. This paper presents an improved solution for interfacial stresses in a concrete beam bonded with the FRP plate by including the effect of the adherend shear deformations. The analysis is based on the deformation compatibility approach where both the shear and normal stresses are assumed to be invariant across the adhesive layer thickness. In the present theoretical analysis, the adherend shear deformations are taken into account by assuming a parabolic shear stress through the thickness of both the concrete beam and the bonded plate. Numerical results from the present analysis are presented both to demonstrate the advantages of the present solution over existing ones and to illustrate the main characteristics of interfacial stress distributions.

Abderezak Rabahi, Belkacem Adim, Selma Chargui, Tahar Hassaine Daouadji

A Sensitivity Analysis of Multi-objective Cooperative Planning Optimization Using NSGA-II

The Non-dominated Sorting Algorithm II (NSGA-II) is one of the most popular genetic algorithms (GA). It is characterized with a high optimization qual- ity that is demonstrated for several multi-objective problems in various disciplines. During the optimization, several genetic parameters are involved and influence the solution quality. The purpose of this paper is to investigate the influence of the NSGA-II parameters on the optimization process, while solving a multi-objective planning model. Two cases, having opposite demand topology, are studied. Results show a considerable impact of NSGA-II parameters, especially the population size and the mutation operators, on the algorithm behaviour and the optimization process. This investigation offers to the partners several optimal production plans with different parameters combinations, and allows them to select the most influential parameter that provide several good solutions.

Wafa Ben Yahia, Omar Ayadi, Faouzi Masmoudi

Transient Flow Analysis through Centrifugal Pumps

A theoretical study has been carried out on the transient flow through a centrifugal pump during the starting period. The problem is governed by two hyperbolic partial differential equations which the continuity and the motion equations. The mathematical model is solved numerically by using the method of characteristics with specified time intervals. The comparison between the obtained numerical results and those obtained by experiment has shown a good concordance. In this study, the effect of the starting time, the impeller diameter, the number and the height of blades on the pressure increase were analyzed. The numerical results have shown that the pressure increase is inversely proportional to the starting time. However, during the starting period, these results have shown that the number of blades has no significant effect on this pressure increase.

Issa Chalghoum, Sami Elaoud, Mohsen Akrout, Ezzeddine Hadj-Taïeb

Vibro-Acoustic Analysis of Laminated Double-Wall: Finite Element Formulation and Reduced-Order Model

This paper presents a finite element model for sound transmission analysis through a double sandwich panels with viscoelastic core inserted in an infinite baffle. The proposed model is derived from a multi-field variational principle involving structural displacement of the panels and acoustic pressure inside the fluid cavity. To solve the vibro-acoustic problem, the plate displacements are expanded as a modal summation of the plate’s real eigenfunctions in vacuo. Similarly, the cavity pressure is expanded as a summation over the modes of the cavity with rigid boundaries. Then, an appropriate reduced-order model with mode acceleration method by adding quasi-static corrections is introduced. The structure is excited by a plane wave. The radiated sound power is calculated by means of a discrete solution of the Rayleigh Integral. Fluid loading is neglected. Various results are presented in order to validate and illustrate the efficiency of the proposed reduced finite element formulation.

Walid Larbi, Jean-François Deü, Roger Ohayon

Time Step Size Effect on the Hydrodynamic Structure around a Water Darrieus Rotor

Turbulent flows are encountered in many hydraulic and water resources engineering problems. Their understanding is thus a critical prerequisite for designing stream and river restoration projects and a broad range of hydrodynamic structures. For this purpose, an unsteady Reynolds averaged Navier-Stokes (URANS) equations with a two-equations turbulence closure model is employed. The present paper aims to numerically explore the three-dimensional unsteady flow over a conventional Darrieus type rotor and to study the time step size effect on the hydrodynamic structure.

Ibrahim Mabrouki, Ahmed Samet, Zied Driss, Mohamed Salah Abid

Simulation of the Dynamic Behavior of a Multi-stage Geared Systems with Tooth Shape Deviations and External Excitations

In this paper, a torsional dynamic model of multi-stage idler spur and helical gears is presented which combines time-varying internal and external excitations such as time-varying external torques. Each contact line in the various base planes is discretized in elemental cells which are all attributed a time-varying mesh stiffness element and an initial separation to account for tooth shape deviations from ideal involute flanks. The corresponding non-linear differential system is solved by combining a Newmark’s numerical scheme and a normal contact algorithm. A number of simulation results are presented on the influence of the combined effect of errors and shape deviations along with external excitation sources on dynamic tooth loads.

Hassen Fakhfakh, Jérome Bruyère, Philippe Velex, Samuel Becquerelle

Fuzzy Modeling and Control of Centrifugal Compressor Used in Gas Pipelines Systems

Respond to changing technology industrial installations, this work propose solutions to the modeling and control problems in industrial processes with the use of new approaches. The objective of this work is the use of fuzzy techniques in modeling and control in the study of gas compression system instability. The obtained results show clearly how the main dynamic characteristics, in our examined compression system, are reproduced using the proposed fuzzy model, allowing better performance during its control synthesis operation.

Ahmed Hafaifa, Guemana Mouloud, Belhadef Rachid

Burst Test and J-Integral Crack Growth Criterion in High Density Poly-Ethylene Pipe Subjected to Internal Pressure

In the present work we are interested on the analysis of the severity of crack defects created by a disc cutter and to study the behavior of a high density polyethylene pipe (HDPE pipe) when subjected to an internal pressure, either in the absence or presence of a pre-crack. In order to do this, experimental tests was performed to measure the toughness and to determine the mechanical behavior of HDPE. These features were used to perform numerical simulations using ABAQUS on pipe solicited by an increase in internal pressure. This allows to compare with burst tests of cracked pipes and to determine the fracture energy that will be compared to the toughness.

The results show that the crack is initiated in the radial direction. And the size of the crack has a great influence on the energy of rupture and consequently on the ultimate pressure. There is a good agreement between experimental and numerical results.

Mohamed Amine Guidara, Mohamed Ali Bouaziz, Christian Schmitt, Julien Capelle, Ezzeddine Hadj-Taïeb, Zitouni Azari, Said Hariri

Solving the Three-Dimensional Time-Harmonic Maxwell Equations by Discontinuous Galerkin Methods Coupled to an Integral Representation

In this paper, we present a numerical study of three-dimensional time-harmonic Maxwell equations. We use a finite element discontinuous Galerkin method coupled with an integral representation. This study was completed by several numerical examples to test the efficiency of the proposed approach. The numerical simulation was down by an iterative solver implemented in FORTRAN.

Nabil Gmati, Stéphane Lanteri, Anis Mohamed

Iterative Methods for Steady State Looped Network Analysis

The aim of this paper is to numerically study the steady state of water flows in looped networks. This study will be performed by the use of Hardy Cross Method and Newton-Raphson algorithm. The comparison of the numerically obtained results by these two methods to those obtained by the use the commercial software Pipe Flow Expert has shown a good concordance between them. The numerical analysis has shown that the convergence of Newton-Raphson method is more rapid than that of the classic Hardy Cross Method.

Zahreddine Hafsi, Sami Elaoud, Mohsen Akrout, Ezzeddine Hadj-Taïeb

Investigation and Modeling of Surface Roughness of Hard Turned AISI 52100 Steel: Tool Vibration Consideration

Since the great interest of the achieved parts quality, this experimental study focuses on the modeling and the investigation of the surface roughness of hard turned AISI 52100 steel. The tool vibration was taking into consideration beside cutting speed, depth of cut, feed rate and tool nose radius. The response surface methodology (RSM) was employed for modeling process. Models reliability was established by conducting confirmation tests. Slight divergence between the experimental and their corresponding predicted values were observed. The significance of the different factors on surface roughness was established by applying analysis of variance (ANOVA). The results revealed that the best surface roughness is obtained by using small feed rate and large nose radius. Furthermore, a correlation between the surface roughness and tool vibrations was established.

Ikhlas Meddour, Mohamed Athmane Yallese, Hamdi Aouici

Finite Element Simulation of Fatigue Damage Accumulation for Repaired Component by Cold Expansion Method

This manuscript investigates the effectiveness of applying the cold expansion process to extend the fatigue life of mechanical structures. During the cold expansion process compressive residual stresses around the expanded hole are generated. The enhancement of fatigue life and the crack initiation and growth behavior of a holed specimen were investigated by using the 6082 Aluminum alloy. The present study suggests a simple technical method for enhancement of fatigue life by a cold expansion hole of pre-cracked specimen. This technique produces beneficial high compressive residual stresses which have been predicted by means of finite element models, both 3D for proper assessment of thickness effects. Finite element models have been developed to increase their complexity, Fatigue damage accumulation of cold expanded hole in aluminum alloy which is widely used in transportation and in aeronautics was analyzed. Experimental tests were carried out using pre-cracked SENT specimens. Tests were performed in two and four block loading under constant amplitude. These tests were performed by using two and four blocks under uniaxial constant amplitude loading. The experimental results were compared to the damage calculated by the Miner’s rule and a new simple fatigue damage indicator based on an energy criterion. This comparison shows that the ‘energy criterion model’, which takes into account the loading history, yields a good estimation according to the experimental results.

Abdelkrim Aid, Mostefa Bendouba, Mohamed Benguediab, Abdewahab Amrouche

Geometrically Non-linear Free Vibration of Fully Clamped Symmetrically Laminated Composite Skew Plates

The present work concerns the geometrically non-linear free vibration of fully clamped symmetrically laminated composite skew plates. The theoretical model based on Hamilton’s principle and spectral analysis previously applied to obtain the non-linear mode shapes and resonance frequencies of thin straight structures, such as beams, plates and shells is used. A convergence study has been performed and has shown that 18 plate functions should be taken into account. Results are given for the linear and non-linear fundamental mode shape of fully clamped symmetrically laminated composite skew plates, considering different parameters such as the skew angle, the number of layers, the fiber orientation, the vibration amplitudes and plate aspect ratio. It was found that the non-linear frequencies increase with increasing the amplitude of vibration and increasing the skew angle, which corresponds to the hardening type effect, expected in similar cases, due to the membrane forces induced by the large vibration amplitudes.

Hanane Moulay Abdelali, Bilal Harras, Rhali Benamar

Scratch Adhesion Characteristics of PVD Cr/CrN Deposited on High Speed Steel and Silicon Substrates

The substrate is one of the significant parameters of technology controlling the mechanical properties of PVD coatings. The quality of the coating is highly influenced by the adhesion. An improvement of these properties can open new areas of applications. In this paper, the adhesion results for PVD Cr/CrN on high speed steel and silicon substrates are presented. The adherence of the coatings to the steel substrate was evaluated using a scratch test. In the scratch test, the critical force as the beginning of spalling or delaminating of the coating was determined. All the coatings show critical values higher than 7 N. The critical load depends on the film thickness and the substrate composition.

Kaouthar Khlifi, Hafedh Dhifelaoui, Ahmed Ben Cheikh Larbi

Load Sharing Behavior in Planetary Gear Set

The objective of this paper is to study the effects of meshing phase between planets, the effects of the gravity of carrier and the planet position error on the load sharing behavior in planetary gear set. These effects will be studied numerically under the stationary condition and will be validated experimentally by a back-to-back planetary gear test bench. In this test bench, strain gauges are installed on each planet’s pin hole in order to compare strains in the pinhole of each planet.

Ahmed Hammami, Miguel Iglesias Santamaria, Alfonso Fernandez Del Rincon, Fakher Chaari, Fernando Viadero Rueda, Mohamed Haddar

Low Velocity Impact Behavior of Glass Fibre-Reinforced Polyamide

The low velocity impact behavior of composites made of polyamide (PA) as matrix and glass fibre as reinforcement has been investigated. The assessment of the impact behavior has driven the need to perform tensile tests to determine the elasto-plastic behavior of the composites. The specimens were manufactured by injection molding techniques for the experimental tensile testing. ABAQUS/EXPLICIT for finite element modeling is employed in order to predict the impact behavior of glass fibre-reinforced polyamide. The determinations of the impact force history and elasto-plastic structure deflection are the most important objectives in impact engineering structures design.

Jamel Mars, Mondher Wali, Remi Delille, Fakhreddine Dammak

Burst Pressure Estimation of Corroded Pipeline Using Damage Mechanics

Pipelines are being widely employed worldwide as means of conveyance of crude oil and its derivatives. Especially in the south and in the north of Algeria many pipelines connect oil fields to oil refineries. Nevertheless, a considerable distance is covered crossing hills, in which landslides could change not only the pipelines alignment but also the stresses. Besides, landslides may cause cracks in the pipes. Furthermore, both the close contact with soil and the action of weather can provide the corrosion of the pipes, which will reduce the cross section area, allowing the formation of disturbed flow areas, and also will develop stress concentrated regions on the pipe wall. Generally, the main cause of high-pressure gas and oil pipeline ruptures is metal loss in a pipe wall from corrosion. Particularly, SONATRACH company data show that corroded defects (general corrosion and pitting corrosion) are the primary causes of accidents. Corrosion is one of the most common causes of accidents involving pipelines. To avoid these undesirable situations, computational models are playing an important role, as they are able to predict the behaviour of pipelines in several ways. . The computational simulation through Finite Element Method (FEM) is one of the most efficient tools to quantify reliably the remaining strength of corroded pipes.

This work presents a new method based on the concept of Continuum Damage Mechanics (CDM) which currently has reached a stage of maturity enabling it to model any type of degradation. The value of the critical pressure, i.e., the allowable operating pressure, of a corroded pipeline is obtained by using a post processor based upon damage mechanics. This post processor allows the calculation of the crack initiation conditions from the history of strain components taken as the output of the ANSYS Software. The ANSYS code is used for physical and geometrical non-linear analysis to obtain the critical point where at any time the damage equivalent stress is maximum. This method was validated by comparing the results of numerical simulations with experimental and ASME/ B31G results available in the literature.

Djebbara Benzerga

Numerical Simulation of Incremental Sheet Metal Forming Process

This paper presents a numerical simulation of the incremental sheet metal forming (ISF) process, type single point incremental forming (SPIF). A finite element model (FEM) is developed by using the commercial FE code ABAQUS. An elasto-plastic constitutive model with quadratic yield criterion of Hill and isotropic hardening behavior has been adopted during ISF operation. Results including thickness variation of sheet metal and forming force along Z-axis are presented.

Lotfi Ben Said, Mondher Wali, Fakhreddine Dammak

A Higher Order Shear Strain Enhanced Solid-Shell Element for Laminated Composites Structures Analysis

This paper presents a free from locking higher order solid-shell element based on the Enhanced Assumed Strain (EAS) for laminated composite structures analysis. The transverse shear strain is divided into two parts: the first one is independent of the thickness coordinate and formulated by the Assumed Natural Strain (ANS) method; the second part is an enhancing part which ensures a quadratic distribution through the thickness. This permit to remove the shear correction factors and improves the accuracy of transverse shear stresses. Also, volumetric locking is completely avoided by using the optimal parameters in the EAS method. Comparisons of numerical results with those extracted from literature show the performance of the developed finite element.

Abdessalem Hajlaoui, Abdessalem Jarraya, Mondher Wali, Fakhreddine Dammak

New Approch of High Cycle Fatigue Behaviour of Defective Material under Multiaxial Loading in 1045 Steel

This paper presents a new approach to predicting the HCF behaviour of defective material submitted to Multiaxial loading .Defects resulting from the casting processes are simplified to semi-spherical pore at surface of specimen. Finite Element (FE) method was used to determine stress distribution around defect. Papadoupolos criterion was used to evaluate stress equivalent around defect. A definition of affected area was given, which is the area close to surface defect where papadoupolos criterion was violated .The evolution of the affected area, with the amplitude of loading and defect size, allows us to determine fatigue limit for different defect sizes. Results of the new approach are in good agreement with experimental results and show that affected area is a good parameter to characterise the influence of a defect on fatigue behaviour.

Hassine Wannes, Anouar Nasr, Chokri Bouraoui

Determination of Stress Concentration for Orthotropic and Isotropic Materials Using Digital Image Correlation (DIC)

The objective of this study was to perform a tensile test on isotropic and orthotropic plates with holes and measured deformations around their hole by using the method of digital image correlation (DIC). The results of this measure were used to determine the local stress at the edge of the hole and measured the net and global stress concentration factor for isotropic and orthotropic materials and see the difference between the two types of materials.

This paper presents an analysis of the net and global stress concentration factor for different hole diameters and their influence on the isotropic and orthotropic material using a camera DIC.

Mhalla Mohamed Makki, Bouraoui Chokri

The Extended Finite Element Method for Cracked Incompressible Hyperelastic Structures Analysis

This paper aims to examine the contribution of the extended finite element method (XFEM) in finite strain fracture mechanics problems. A generalized neo-Hookean hyperelastic material is considered in an incompressible plane stress approximation. The accuracy of the implementation is demonstrated by a series of numerical tests.

Mehrez Zaafouri, Mondher Wali, Said Abid, Mohammed Jamal, Fakhreddine Dammak

Displacement Influence on Frequencies and Modal Deformations of a Sandwich Beam

Composite structures are used in the aerospace, stars and automotive especially the structures made of composite sandwich panels which are subject to vibration harmful sources of noise and mechanical failures. In this paper, we propose to analyze the influence of the shapes of displacement fields on the vibration behavior of a sandwich beam. For this energy method based on the minimum energy is used to achieve the equations frequencies and a sandwich beam modes. The kinetic and potential energies of the skins are, in turn, derived from the classical laminate theory. Several fields of polynomial movements are tested. Other parts will study the effects of rotational inertia, taking into account the bending energy of the body of sandwich NIDA. We analyzed the frequencies and modes based on different parameters. The experimental data are obtained for recessed-free conditions limits exciting near underrun using an impact hammer. The vibrational response is measured with a laser vibrometer. The natural frequencies are obtained experimentally by modal analysis. Numerical simulations complete this work for two types of sandwich Nomex paper and aluminum. The natural frequencies obtained from the theoretical formulation for numerical solution of the system are compared with experimental results and the results of numerical simulation. The very good agreement between the results shows that the model is correct.

Idris Chenini, Youssef Abdelli, Rachid Nasri

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