Tilting-Pad Journal Bearings (TPJB) are commonly used on high-performance turbomachinerydue to their excellent stability properties at high speed when compared to other designsfor oil film bearings. Hence, efforts have been made to improve the accuracy for theavailable models for these mechanical devices, achieving nowadays anelasto-thermo-hydrodynamic formulation. On the other hand, the basic design of theTilting-Pad Journal Bearing has been modified in order to transform it into a smartmachine element. One approach to do so is to inject pressurized oil directly into thebearing clearance through holes drilled across the bearing pads. By adjusting theinjection pressure, it is possible to modify the dynamic characteristics of the bearing. Acontrollable lubrication regime is obtained, allowing to expand the operational boundariesof the original design. This work focuses on presenting an elasto-thermo-hydrodynamicmodel (ETHD) for the Tilting-Pad Journal Bearing, including the effect ofthe controllable lubrication system. The basic model is validated by comparing its resultsagainst theoretical and experimental results available in the literature. Then, thevalidated code is used to show the benefits of applying a controllable lubrication regime,by means of the modification of the thermal and dynamic behaviour of the bearing.

The present work fosters experimental measurements and mathematical modelling techniquesto primarily determine the thermal and the relative humidity characteristics in theair-conditioned surgical operating room. The present work also demonstrates the effect ofthe various designs of surgical operating rooms and operational parameters on the flowpattern and temperatures characteristics. This study is a part of a more comprehensiveinvestigation of the more important factors affecting the air environments in surgicaloperating room. Measured and predicted temperatures and relative humidity profiles areshown to be in good agreement. The present paper introduces several recommendationsregarding the optimum design requirements of operating rooms to provide hygiene andcomfort environment. Low humidity affects comfort and health. The present work offersexamples of measured relative humidity profiles in an operating room in (New Kasr El-AiniTeaching Hospital – 1200 beds – Cairo University – Egypt). These experimental results werecarried out to verify the proposed numerical procedure and particularly in the vicinity ofthe supply outlets and operating table.

Evaluation of the dynamic properties of quasi-brittle materials is of the utmostimportance for assessing the vulnerability of structural components under dynamic loadingssuch as collision or explosion. To investigate the dynamic strength of (quasi)-brittlematerial, three-point bending tests are performed on a modified Split Hopkinson PressureBar. Such an apparatus is often used with pre-cracked specimen to determine the dynamicstress intensity factor of metallic materials. With quasi-brittle materials special carehas to be paid to the processing of the test since fracture can occur at very low strains.The specimen remains in an out-of equilibrium state and fracture occurs before the supportreactions appear as if it was a support-free impact test. A special non-equilibriumanalytical approach has been developed to process the tests. Finite-element simulationsare used to assess relevance of the proposed analysis for normalized short beams.Experimental results on brick and concrete samples showing a significant dynamic strengthincrease are presented.

In this paper, strain gradient theory is used in developing a mathematical model based on classical flexural Kirchhoff plate theory that can predict static response of rectangular micro-plates. The result of this new model is a sixth order differential equation. Order of differential terms in Galerkin weak form of the equation is reduced so that C2 hierarchical p-version finite elements with second order global smoothness can be used to solve the problem. With different boundary conditions, the computed deflection distribution of micro-plates is compared with those of the classical theory, in which length scale parameters are not present. A series of studies have revealed that when length scale parameters are considered, deflection of a rectangular plate decreases with increasing the length scale effect; in other words micro plates exhibit more rigidity than what is predicted by the classic model. Here, deflections are normalized with respect to results obtained from classical plate theory. Comparison of maximum deflection values obtained from the extended model for micro plates with those available from the classic plate model indicates that classical theory overestimates displacement values and the largest error is observed for square micro plates. The overestimation levels off for plates with aspect ratios greater than three.

This paper synthesizes a whole of work carried out on the spiral bevel gears fromquasi-static and dynamic models viewpoint. A sophisticated quasi-static model makes itpossible to calculate the tooth loads, the pressures, the instant mesh stiffness, and thedeflections on the flanks of spiral bevel gears. Based on these results, twothree-dimensional lumped parameter dynamic models are presented. The mechanical systemunder consideration comprises: a spiral bevel pinion and gear connected by a time-varyingnon-linear mesh stiffness function, and mounted on two shafts simulated by Timoshenko’sbeams supported by bearings. Two variants are considered which rely on different contactstiffness simulations: (a) using an averaged mesh stiffness function acting at thecentroid of the loaded areas on tooth flanks and (b) a more local approach based on adiscrete distribution of the local mesh stiffness, elements over the contact areas. Anumber of results are presented and commented which illustrate the interest of thesedynamic models.

The sheet metal forming by shearing is one of the most used processes in industries. The reliability of the obtained parts depends on geometrical parameters (shape of the tools, punch radius, clearances, velocity...) and materials properties (metal behavior, friction...). In this paper, two experimental parameters are investigated: the punch – die clearance and the punch velocity. A 0.65 mm thickness sheet of a non-oriented full-process Fe-(wt.3%)Si is used. The analyses are done through the load-stroke curve and the height repartition of different defects on the part edge. A numerical approach is proposed to simulate the shearing process and to handle the ductile fracture (which is performed using Abaqus/Explicit software). This work is based on a non-iterative explicit algorithm combined with a mesh adaptivity method (Arbitrary Lagrangian Eulerian formulation). The Gurson–Tvergaard–Needleman model is then used to describe the cut edge profile occurring during the process.

This paper is based on additional treatments of the experimental results obtained by L. Bodelot, L. Sabatier, E. Charkaluk, P. Dufrénoy [Experimental setup for fully coupled kinematic and thermal measurements at the microstructure scale of an AISI 316l steel, Mater. Sci. Eng. A 501 (2009) 52–60]. In order to perform inter- and intragranular thermomechanical analyses in a metallic polycrystal at the grain scale, a crystallography-based projection technique of the thermal and displacement fields on a polynomial basis is proposed. It enables intragranular coupled analysis of strain and temperature full-field data consistent with the plastic slip activation observed on specimen surface after the test.

The studied movement is the “offset” skating technique. It is typically used by the skierfor higher-force-requirement situations: climbing up a hill, handling conditions (slowsnow or head-wind) or in low force situations. It is a thrust with the both poles for eachfull stroke-cycle of the legs. Firstly, we have made a model of a skier for a movementcycle and secondly a mechanical analysis to validate this model. This work was made thanksto the biomechanics software “LifeModeler”, plug-in of ADAMS software, which is akinematic and dynamic simulation tool. LifeModeler creates a human body as ananthropomorphic robot and ADAMS allows equipping it with tools and placing it on a ground.We have built a dynamic model in 3D for the skier in its environment, that is, with itsequipment on the snow. The final goal is to analyze performances parameters effect and tomaximize the movement effectiveness, what is possible by perfecting gesture, equipment andby optimizing materials used in this sport.

This paper presents the application of new time frequency method, ensemble empirical modedecomposition (EEMD), in purpose to detect localized faults of damage at an early stage.EEMD is a self adaptive analysis method for non-linear and non-stationary signals and itwas recently proposed by Huang and Wu to overcome the drawbacks of the traditionalempirical mode decomposition (EMD). The vibration signal is usually noisy. To detect thefault at an early stage of its development, generally the residual signal is used. Thereexist different methods in literature to calculate the residual signal, in this paper wemention some of them and we propose a new method which is based on EEMD. The results givenby the different methods are compared by using simulated and experimental signals.

In this paper, the cyclostationary characteristics of electrical signals will beexploited in order to detect the rotor faults of an asynchronous machine. These defectsare the most complex in terms of detection since they interact with the 50 Hz carrier witha weak band occupied in frequency. The testing ground used includes an industrialthree-phase wound rotor asynchronous motor of 400 V, 6.2 A, 50 Hz, 3 kW, 1385 rpmcharacteristics. The rotor fault has been carried out by adding an extra 40 mΩ resistanceon one of the rotor phases (i.e. 10% of the rotor resistance value per phase,Rr = 0.4Ω). From the stator voltage andcurrent acquisition, and by application of the Time Synchronous Averaging (TSA) method tothe stator current, the electrical signal will be conditioned in order to obtain asensitive indicator allowing to easily distinguish the healthy cases from defective ones.

Braking operation is a process which converts the kinetic energy and the potential energyof the vehicle into other energies. The major part of the mechanical energy is transformedinto heat. During the braking phase, the frictional heat generated at the interfacedisc–pads can lead to high temperatures. This phenomenon is even more important that thetangential stress as well as the relative sliding speeds in contact are important. Theobjective of this study is to analyse the thermal behavior of the full and ventilatedbrake discs of the vehicles using computing code ANSYS. The modeling of the temperaturedistribution in the disc brake is used to identify all the factors and the enteringparameters concerned at the time of the braking operation such as the type of braking, thegeometric design of the disc and the used material. The results obtained by the numericalsimulation are satisfactory compared with those of the specialized literature.

Thermoplastic based composites containing different weight fractions of molybdenumdisulfide (MoS2) solid lubricant were developed by injection molding.Polymethyl methacrylate (PMMA) and polycarbonate (PC) were chosen for the thermoplasticmatrices. In order to characterize the interfacial adhesion between the matrices and thefiller, we observed the fracture morphologies of selected composites. Micrographs of thefractured surfaces showed removal of MoS2 particles by microcraking as well asthe presence of voids in the case of PMMA/MoS2 composites. These observationswere confirmed by complementary images obtained using the X-ray tomography. The additionof an appropriate coupling agent may improve the adhesion between the MoS2particles and the polymer matrix. Tribological behavior of the composites was alsoinvestigated using a ball-on-flat microtribometer with a high chromium steel ballantagonist. It was found that the addition of MoS2 particles didn’t improve thetribological performance of the composite in the case of PMMA matrix unlike the case of PCmatrix where the friction coefficient was considerably reduced.

In this study, numerical models based on finite-element method are developed for severalapplications of fracture mechanics. The use of cracked specimens formed by differentmaterial properties has allowed us to analyse the effect of the crack position to theinterface and to have a well understanding of mismatch effect for the case of mixed modeof fracture. In other hand, we have noticed that it is very interesting to see the effectof the interface position and loading for the case of symmetrically cracked ring specimenunder compression loading.

In this paper, an analytical approach is proposed to model chip formation in the case ofturning process. Numerical simulations of chip genesis are performed in order to fitefficiently the proposed analy- tical model. In particular, cutting edge radius influence,temperature and internal stresses distribution are studied using finite element modelling.Numerical model setting is made with experimental and literature data using forces andchip thickness.

On étudie expérimentalement l’écoulement turbulent pariétal produit par l’impact d’un jet frappant normalement un disque coaxial en rotation. La méthode utilisée est l’anémométrie à fil chaud : on mesure les vitesses moyennes, ainsi que les contraintes turbulentes dans un domaine où les effets de l’alimentation par le jet axial et ceux de la rotation du disque sont du même ordre de grandeur. On se place dans le cadre des approximations de couche limite pour obtenir une formulation simplifiée du problème. Par ailleurs, on met en évidence les paramètres sans dimensions qui jouent un rôle significatif. L’étude expérimentale est conduite en faisant varier ces paramètres. L’analyse des résultats expérimentaux fournit les échelles caractéristiques des vitesses et des longueurs, ainsi que le niveau de turbulence. De plus, elle donne des informations sur l’importance relative des différents termes des équations de Reynolds et permet de vérifier la validité de l’approximation de couche limite.

Dimensional errors of the parts from a part family cause the initial misplacement of theworkpiece on the fixture affecting the final product quality. Even if the part ispositioned correctly, the external machining forces and clamping load cause the part todeviate from its position. This deviation depends on the external load and the fixturestiffness. In this article, a comprehensive analytical model of a 3-2-1 fixturing systemis proposed, consisting of a kinematic and a mechanical part. The kinematic modelrelocates the initially misplaced workpiece in the machine reference through the axialadvancements of six locators taking all the fixturing elements to be rigid. Therepositioned part then shifts again from the corrected position due to the deformation offixturing elements under clamping and machining forces. The mechanical model calculatesthis displacement of the part considering the locators and clamps to be elastic. The rigidcuboid baseplate, used to precisely relocate the workpiece, is also considered elastic atthe interface with the locators. Using small displacement hypothesis with zero friction atthe contact points, Lagrangian formulation enables us to calculate the rigid bodydisplacement of the workpiece, deformation of each locator, as well as the stiffnessmatrix and mechanical behavior of the fixturing system. This displacement of the workpieceis then finally compensated by the advancement of the six axial locators calculatedthrough the kinematic model.

Numerical simulations of the isothermal turbulent jets mixing flows exhausted from twodifferent circular lobed nozzles are presented in the present paper. The numerical studieshave been conducted using a Favre-Reynolds Averaged Navier-Stokes approach, using thesecond-order Reynolds Stress Model (RSM) and structured mesh. Thevalidation of the numerical results with experimental data has been carried out only withone nozzle for the same configuration. This comparison shows reasonable agreement,principally, in terms of centreline longitudinal velocity, longitudinal fluctuatingvelocity and streamwise vorticity. In the second part, the effects of the inlet isothermallobed jet on the mixing process with variable density have been studied numerically. Forthe same area exit geometries (axisymmetric and asymmetric), a qualitative comparison ofthe numerical results with experimental data have been presented. All these indicated thebetter mixing enhancement performance of a lobed nozzle over asymmetric and axisymmetricnozzles respectively.

Stirred bead mills used in industry allow to split up particules in suspension byagitating a milling medium. The multiple impacts may damage beads and thus reduce thestirred milling process efficiency. A discrete numerical approach including simple fluideffects is proposed and carried out in this paper to model and study finely the damagephenomenon. The simulation data allow to identify internal variables of the milling mediumand to localize high energy zones. The order of magnitude of contact forces includingfluid contribution will enhance the bead wear law.

Probability Density Function (PDF) is often selected to couple chemistry with turbulencefor complex reactive flows since complex reactions can be treated without modelingassumptions. This paper describes an investigation into the use of the particlesapproximation of this transport equation approach applied to Homogeneous ChargeCompression Ignition (HCCI) combustion. The model used here is an IEM (Interaction byExchange with the Mean) model to describe the micromixing. Therefore, the fluid within thecombustion chamber is represented by a number of computational particles. Each particleevolves function of the rate of change due to the chemical reaction term and the mixingterm. The chemical reaction term is calculated using a reduced mechanism of n-heptaneoxidation with 25 species and 25 reactions developed previously. The parametric study witha variation of the number of particles from 50 up to 104 has been investigatedfor three initial distributions. The numerical experiments have shown that the hatdistribution is not appropriate and the normal and lognormal distributions give the sametrends. As expected when the number of particles increases for homogenous mixture (i.e.high turbulence intensity), the in-cylinder pressure evolution tends towards thehomogeneous curve. For both homogeneous and inhomogeneous (i.e. low turbulence intensity)cases, we have found that 200 particles are sufficient to model correctly the system, witha CPU time of a few minutes when a restriction of initial distribution is adopted.

Une double enceinte climatique conçue sur le principe de la méthode de la boîte chaudegardée a été mise au point afin d’étudier en laboratoire le comportement thermique ethygrique de différentes configurations de parois en bois. Le dispositif est dotéd’équipements de régulation lui permettant de reproduire des sollicitations climatiquesstationnaires ou dynamiques proches d’un climat réel et de suivre l’évolution des profilsde température et d’humidité dans les parois testées. Dans ce travail, le suivi ducomportement hygrothermique d’une paroi en ossature bois comportant des matériauxhygroscopiques et soumises à différentes conditions est rapporté. Les résultats ont montréque la capacité du dispositif à bien reproduire les conditions imposées a permis demesurer les propriétés importantes de parois en régime permanent (résistance thermique) ettransitoire (amortissement et déphasage thermique). Les essais réalisés ont également misen évidence le comportement hygroscopique des matériaux testés.