Additive manufacturing processes, used for more than 25 years, are no longer confined torapid prototyping applications. Mostly used nowadays in niche markets (medicalapplications, aerospace...) to manufacture metallic parts, they should provideimprovements in terms of time-to-market, ecological impact and design compared totraditional industrial processes. Current metallic additive manufacturing studied in thispaper are Selective Laser Sintering, Direct Metal Laser Sintering, Selective LaserMelting, Electron Beam Melting and Direct Metal Deposition. The performances of theseprocesses are investigated through criteria derived from the time cost quality triangleand some prospects concerning these processes are given.

In this study, the dynamic analysis of Pipeline Inspection Gauge (PIG) flow control innatural gas and liquid pipeline is considered. The basic equations are differential formsof the mass and linear momentum for compressible liquid and gas flows. The fluid flowequations and a linear momentum equation of the PIG are solved simultaneously using anappropriate numerical method. Solution of these nonlinear equations results in a set ofdiagrams for the variations of the fluid pressure, mass flow rate of the gas and the PIGvelocity through the pipeline. Comparing the results of mathematical model for the PIGwith the established experimental data in a segment of Ahwaz gas pipeline shows a goodagreement between the measurements and computations.

In this paper, the mechanical properties of plasma-sprayed coatings are evaluated usingthe technology of nanoindentation. According to the indentation curve (load versusindenter’s displacement), which is recorded in an indentation experiment, the mechanicalbehaviour of the plasma-sprayed coating is investigated via inverse analysis usingnumerical optimization algorithms. The tip rounding of imperfect indenter is investigatedin parameter identification. Subsequently, the hardness on the top surface and on thevertical cross section of the plasma-sprayed coating are investigated. The results showthat the hardness on the top surface of the coating depends on the indentation depth.Moreover, the results show that the hardness on the cross section of the coating issignificantly affected by the substrate if the indentation impression is too close to thecoating-substrate interface.

This paper shows that the dynamic study of a railway vehicle in curve can be reduced tothe study of a bogie and two wheelsets in the quasi-static case. Every wheelset supportsthe load of the quarter of the vehicle. From this model, we can optimize the suspension todefine the mechanical build characteristics of vehicle.

Due to their stability under high mechanical and thermal loads nickel-based alloys generate high cutting forces and temperatures during machining which adversely affect tool life. Especially in broaching with form shaped tools, deviations from the original tool geometry cause an inacceptable product quality. In aero engine industry, where quality standards for machining of safety critical parts are very high, this cannot be tolerated. Because of its tool geometry broaching is different from other machining processes: due to the high ratio between cutting edge radius and chipping thickness, the influence of the tool wear at the cutting edge is strong, especially for the finishing section. In order to guarantee stable machining processes in production, monitoring methods are desired that are capable to recognize changes in cutting conditions. The EU funded ACCENT project focuses on this challenge: the goal is to use process monitoring to make conclusions about the product quality during machining and, if necessary make adjustments to process input parameters to keep the quality measures in a defined window.

Most of the norms used in the field of digital image (and volume) correlation to registertwo images (or volumes) lead to ill-posed problems. One of the frequent solutions is toenforce a restricted kinematics requiring a compromise between the richness of thesolution (i.e., the spatial resolution) and the measurement uncertainty. An alternativeroute is to use a displacement norm that permits to alleviate this compromise by the meansof a mechanical regularization used when the gray levels do not give enough information.It is then possible to compute a displacement vector for each pixel orvoxel, inducing lower residuals (in terms of experimental data) whiledecreasing the noise sensitivity. The resolution performance of these different approachesis discussed, and compared for the analysis of a tensile test on a cast iron specimenbased on a pair of tomographic images. As representative reconstructed volumes lead to alarge number of degrees of freedom, a dedicated GPU computational strategy has beendeveloped and implemented.

This paper presents a ductile damage-gradient based nonlocal and fully coupledelastoplastic constitutive equations by adding a Helmholtz equation to regularize theinitial and boundary value problem (IBVP) exhibiting some damage induced softening. First,a thermodynamically-consistent formulation of gradient-regularized plasticity fullycoupled with isotropic ductile damage and accounting for mixed non linear isotropic andkinematic hardening is presented. For the sake of simplicity, only a simplified version ofthis model based on von Mises isotropic yield function and accounting for the singlenonlinear isotropic hardening is studied and implemented numerically using an in house FEcode. An additional partial differential equation governing the evolution of the nonlocalisotropic damage is added to the equilibrium equations and the associated weak formsderived to define the IBVP (initial and boundary value problem). After the time and spacediscretization, two algebraic equations: one highly nonlinear associated with theequilibrium equation and the second purely linear associated with the damage non localityequation are obtained. Over a typical load increment, the first equation is solvediteratively thanks to the Newton-Raphson scheme and the second equation is solved directlyto compute the nonlocal damage \hbox{$\Bar{{D}}$}D̅ at each node. All the constitutive equations are “strongly” affected bythis nonlocal damage variable transferred to each integration point. Some applicationsshow the ability of the proposed approach to obtain a mesh independent solution for afixed value of the length scale parameter. Comparisons between fully local and nonlocalsolutions are given.

In the present study, an enriched continuum mechanics framework is employed to study thesurface effects on bending behavior of silver nanowires (NWs) resting on elasticsubstrate. The Timoshenko beam theory and the Laplace-Young equation are employed toinvestigate static behavior of silver NWs lying on Winkler-Pasternak elastic substrate.Three types of boundary conditions are considered as doubly simply supported (S-S), doublyclamped (C-C) and cantilevered (C-F). Analytical solutions are obtained for NWs withsurface crystallographic orientation of [001] subjected to a concentrated external force.By defining different normalized contact stiffness, extensive numerical results arecarried out to study the influence of effective parameters such as substrate, surface,aspect ratio (L/D) and diameter onthe stiffness of NWs. According to the obtained results, the effect of surface and itsrate of variation on stiffness of NWs lying on Winkler and Winkler-Pasternak elasticfoundation models are more significant in (C-F) type of boundary condition compared to theNWs without foundation. By increasing the modulus of elastic substrate, the effect ofshear deformation increases which it is more considerable in (C-C) and (S-S) NWs restingon the Winkler-Pasternak and Winkler substrate models, respectively.

Safflower is an oil-seed crop with high quality oil that is used for producing healthyfoods and painting colors. This crop has valuable petals which have a lot of uses inmedicine, production of food colors and dyes for coloring fabrics, but such problem asdispersion of flowers, thorns of crops that hurt worker’s hands also lack of a suitableharvesting machine have enforced farmers to harvest petals by hand that is a hard work andnon-economic. In this study a prototype machine was designed and constructed. This machineincludes an engine, a radial fan with BI blades, a snout, a diffuser to separate petalsfrom airflow and a store; all parts are assembled on a trolley to move easily in farm.This machine picks safflower petals out and intakes through snout by the fan suctionpower. Petals go to diffuser where they are separated from airflow then fall to the store.Velocity of airflow in the snout was determined by a fan test duct in order to designdiffuser. At last three farms were harvested by this machine for economic analysis.Results show 657% increasing in amount of harvested petals by harvester machine incomparison with hand harvesting.

Conventional methods (i.e. time, frequency and cepstrum) can routinely be used to revealfault-indicating information in the vibration signal. In recent years, wavelet analysis,which can lead to a clear identification of the nature of faults, is widely used todescribe rotating machine condition. The capability of this method in the detection of anyabnormality can be further improved when its low-order frequency moments are considered.This paper presents the use of the fast kurtogram in the early detection and conditionmonitoring of pitting fault. For this purpose, a dynamic model of a simple stage gearbox(with and without defects) is used. Then, the pinion’s vibration displacement is analyzedby using a fast kurtogram method. This method is suitable for such diagnosis and givesvaluable information about the presence and effects of the pitting tooth defect.

Osteoporosis is a disease characterized by a loss of bone density and an altered bonearchitecture. These modifications lead to an increased risk factor for bone fracture,particularly of the femoral neck. This disease can be explained by a disorder in the boneremodeling process which is triggered by the apparition of micro-cracks within the bone.According to Frost’s theory [1], these micro-cracksappear for a specific local strain threshold. Thus, the knowledge of the microarchitectureand quality of trabecular bone is essential to determine this local strain threshold. Thispaper studied the mechanical trabecular bone behavior of 43 patients diagnosed asosteoporotic whose femoral heads were replaced by hip prosthesis. From each patient, acylinder-shaped of trabecular bone samples was cored. Each sample was scanned by X-raymicro-tomography before a compression test in order to reconstruct a reliableFinite-Element (FE) model of the bone architecture in Abaqus. The force-displacementcurves were recorded for all the samples and calibrated by the experimental responses. Theforce-displacement numerical curves were adjusted to the experimental ones, by modifyingthe tissue microscopic mechanical behavior. This process leads to the determination of thelocal strain threshold responsible for triggering the bone remodeling process.

In industrial area, drilling is one of the most commonly used machining operations. Today, conventional drilling methods have found their limits in deep hole drilling. To be able to push these limits, we have developed a new technology: vibratory drilling. The aim of this study is to determine the influence of the twist drill geometry on performance of the self vibratory drilling head. For that reason, it is necessary to identify the geometrical properties which have the strongest influence on axial vibrations of twist drill and on chip fragmentation. Moreover, we have also validated the experimental results by a simulator which can predict the behaviour of the self vibratory drilling head by taking into account geometrical defects of the tool.

Measurement of heat fluxes and electrodes temperature in a proton exchange membrane fuel cell were performed using platinum wires and heat flux sensors. A temperature difference of 6 °C to 9 °C between the electrodes and the bipolar plates was observed for a cell operating at a current density of 1.5 A.cm-2. These measurements show a strong non-uniformity of the temperature profile through the membrane electrode assembly that future models should take into account. Simultaneous heat fluxes measurements have allowed to evaluate in situ the effective thermal conductivity of the porous layers. Values of the order of 0.3 W.m-1.K-1 were found.

Vibration and wear debris analyses are the two main conditions monitoring techniques for machinery maintenance and fault diagnosis. In addition, numerical simulation can provide useful tools to assess the proper functioning of industrial machines. We use different suspension theories with a concern of the effect of solid particles liquid lubricant itself on bearing behavior. We consider both simple models based on the Einstein’s mixture theory and a micropolar fluid theory, which is characterized by the presence of suspended rigid micro-structured particles. We suppose in this study that there are no abrasion and no wear (which are not beneficial for the contact performances) due to the presence of particles. Thus in this case we found theoretically that the presence of rigid particles in the lubricant increases the effective viscosity which enhances the load-carrying capacity as well as the minimum film thickness.

The market demand for machining and cutting of various plastics parts is in continuousincrease. The aim of this study is to extract prediction laws for surface roughness,cutting forces and temperatures evolution during the machining of two polyethylene pipesgrades (HDPE-100) and (HDPE-80). It was found that feed rate is the most prevailing factoron roughness criteria and that better surfaces are obtained during the machining of theharder HDPE-80 resin. Also, cutting speed improved surface quality for speeds up to 200m.min-1 but the rising interface temperature caused surface damage andmaterial rapid softening. Also, feed exponents, in mathematical models, were found to be 3to 4 times higher than those of cutting speed and depth of cut. An increase in the cuttingspeed led to a gradual reduction for the 3 cutting forces components (Fr,Fa and Fv) with a dominance of the tangential force(Fv). As expected, the value of the depth of cut had a large influenceon the temperature within the cutting zone. This temperature is slightly higher during themachining of HDPE-80 compared to that of HDPE-100 most probably because of hardnessdifferences. The analysis of variance (ANOVA) was performed to check the adequacy of themathematical models relating cutting parameters with roughness, cutting forces and globalcutting zone temperature.

This paper presents experimental and numerical studies of drop tests of corrugatedcardboard packaging containing different foam cushions. An efficient homogenization modelfor the corrugated cardboard has been developed. In our homogenized model, the corrugatedcardboard is represented by a 2D plate. Instead of using a local constitutive law(relating the strains to the stresses) at each material point, the homogenization givesthe global rigidities (relating the generalized strains to the resultant forces) for theequivalent homogeneous plate. This model was implemented into the FE software ABAQUS. Thefoam behaviour was experimentally determined and modelled using a crushable foam model ofABAQUS. The packages are tested in free fall from a given height on a rigid floor. Thedeceleration of the packed product was recorded using a triaxial accelerometer. Thenumerical results obtained using the FE simulation with the homogenized model agree wellwith the experimental results. We have also shown that the contribution of the corrugatedcardboard box to the shock response could not be neglected in the design of cushioningpackage.

This paper investigates the windage power losses generated by spur gears rotating in pureair by using a computational fluid dynamics (CFD) code. The three-dimensional simulationsare at first validated comparing CFD predictions with the power losses measured in similarconditions from other investigations. The volumetric flow rate which is expelled by theteeth is then analysed, and a correlation which is based on a classical approach used inturbomachinery is finally proposed which makes it possible to estimate windage losses forspur gears. It was observed that this latter approach seems satisfying since theformulation of the volumetric flow rate which is employed in the model is appropriate toeach gear.

The study of nonlinear dynamic behavior of laminate composed of steel and rubber layersalso referred as “Shim”, used for vibro-acoustic insulation in brake system, isinvestigated. The simulation of the vibro-acoustic nonlinear behavior of Shim depending onfrequency, taking into account the large deformations and various nonlinearhyper-viscoelastic laws of rubber are considered. This paper presents a solution tocontribute in the identification of the best design of Shim in terms of damping vibrationof brake systems, using analytical and numerical method. The choice of the best structuredepends essentially on the nature of rubber, on the stacking sequence of materials, ontheir thickness, on the number of layers and on volume fraction of rubber. An analyticalstudy, with the use of the transfer matrix method is presented. A model on the finiteelement software ANSYS is constructed. The results lead to conclusions about the beststructure and design of Shim in term of vibro-acoustic insulation.