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

In this study, the dynamic analysis of Pipeline Inspection Gauge (PIG) flow control in natural gas and liquid pipeline is considered. The basic equations are differential forms of the mass and linear momentum for compressible liquid and gas flows. The fluid flow equations and a linear momentum equation of the PIG are solved simultaneously using an appropriate numerical method. Solution of these nonlinear equations results in a set of diagrams for the variations of the fluid pressure, mass flow rate of the gas and the PIG velocity through the pipeline. Comparing the results of mathematical model for the PIG with the established experimental data in a segment of Ahwaz gas pipeline shows a good agreement between the measurements and computations.

In this paper, the mechanical properties of plasma-sprayed coatings are evaluated using the technology of nanoindentation. According to the indentation curve (load versus indenter’s displacement), which is recorded in an indentation experiment, the mechanical behaviour of the plasma-sprayed coating is investigated via inverse analysis using numerical optimization algorithms. The tip rounding of imperfect indenter is investigated in parameter identification. Subsequently, the hardness on the top surface and on the vertical cross section of the plasma-sprayed coating are investigated. The results show that 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 is significantly affected by the substrate if the indentation impression is too close to the coating-substrate interface.

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

Most of the norms used in the field of digital image (and volume) correlation to register two images (or volumes) lead to ill-posed problems. One of the frequent solutions is to enforce a restricted kinematics requiring a compromise between the richness of the solution (i.e., the spatial resolution) and the measurement uncertainty. An alternative route is to use a displacement norm that permits to alleviate this compromise by the means of 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 or voxel, inducing lower residuals (in terms of experimental data) while decreasing the noise sensitivity. The resolution performance of these different approaches is discussed, and compared for the analysis of a tensile test on a cast iron specimen based on a pair of tomographic images. As representative reconstructed volumes lead to a large number of degrees of freedom, a dedicated GPU computational strategy has been developed and implemented.

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.

This paper presents a ductile damage-gradient based nonlocal and fully coupled elastoplastic constitutive equations by adding a Helmholtz equation to regularize the initial and boundary value problem (IBVP) exhibiting some damage induced softening. First, a thermodynamically-consistent formulation of gradient-regularized plasticity fully coupled with isotropic ductile damage and accounting for mixed non linear isotropic and kinematic hardening is presented. For the sake of simplicity, only a simplified version of this model based on von Mises isotropic yield function and accounting for the single nonlinear isotropic hardening is studied and implemented numerically using an in house FE code. An additional partial differential equation governing the evolution of the nonlocal isotropic damage is added to the equilibrium equations and the associated weak forms derived to define the IBVP (initial and boundary value problem). After the time and space discretization, two algebraic equations: one highly nonlinear associated with the equilibrium equation and the second purely linear associated with the damage non locality equation are obtained. Over a typical load increment, the first equation is solved iteratively thanks to the Newton-Raphson scheme and the second equation is solved directly to compute the nonlocal damage \hbox{$\Bar{{D}}$}D̅ at each node. All the constitutive equations are “strongly” affected by this nonlocal damage variable transferred to each integration point. Some applications show the ability of the proposed approach to obtain a mesh independent solution for a fixed value of the length scale parameter. Comparisons between fully local and nonlocal solutions are given.

Safflower is an oil-seed crop with high quality oil that is used for producing healthy foods and painting colors. This crop has valuable petals which have a lot of uses in medicine, production of food colors and dyes for coloring fabrics, but such problem as dispersion of flowers, thorns of crops that hurt worker’s hands also lack of a suitable harvesting machine have enforced farmers to harvest petals by hand that is a hard work and non-economic. In this study a prototype machine was designed and constructed. This machine includes an engine, a radial fan with BI blades, a snout, a diffuser to separate petals from 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 suction power. 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 design diffuser. At last three farms were harvested by this machine for economic analysis. Results show 657% increasing in amount of harvested petals by harvester machine in comparison with hand harvesting.

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

Conventional methods (i.e. time, frequency and cepstrum) can routinely be used to reveal fault-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 to describe rotating machine condition. The capability of this method in the detection of any abnormality 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 condition monitoring 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 analyzed by using a fast kurtogram method. This method is suitable for such diagnosis and gives valuable 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 bone architecture. 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 bone remodeling process which is triggered by the apparition of micro-cracks within the bone. According to Frost’s theory [1], these micro-cracks appear for a specific local strain threshold. Thus, the knowledge of the microarchitecture and quality of trabecular bone is essential to determine this local strain threshold. This paper studied the mechanical trabecular bone behavior of 43 patients diagnosed as osteoporotic whose femoral heads were replaced by hip prosthesis. From each patient, a cylinder-shaped of trabecular bone samples was cored. Each sample was scanned by X-ray micro-tomography before a compression test in order to reconstruct a reliable Finite-Element (FE) model of the bone architecture in Abaqus. The force-displacement curves were recorded for all the samples and calibrated by the experimental responses. The force-displacement numerical curves were adjusted to the experimental ones, by modifying the tissue microscopic mechanical behavior. This process leads to the determination of the local 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 continuous increase. The aim of this study is to extract prediction laws for surface roughness, cutting forces and temperatures evolution during the machining of two polyethylene pipes grades (HDPE-100) and (HDPE-80). It was found that feed rate is the most prevailing factor on roughness criteria and that better surfaces are obtained during the machining of the harder HDPE-80 resin. Also, cutting speed improved surface quality for speeds up to 200 m.min-1 but the rising interface temperature caused surface damage and material rapid softening. Also, feed exponents, in mathematical models, were found to be 3 to 4 times higher than those of cutting speed and depth of cut. An increase in the cutting speed 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 influence on the temperature within the cutting zone. This temperature is slightly higher during the machining of HDPE-80 compared to that of HDPE-100 most probably because of hardness differences. The analysis of variance (ANOVA) was performed to check the adequacy of the mathematical models relating cutting parameters with roughness, cutting forces and global cutting zone temperature.

This paper presents experimental and numerical studies of drop tests of corrugated cardboard packaging containing different foam cushions. An efficient homogenization model for the corrugated cardboard has been developed. In our homogenized model, the corrugated cardboard 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 gives the global rigidities (relating the generalized strains to the resultant forces) for the equivalent homogeneous plate. This model was implemented into the FE software ABAQUS. The foam behaviour was experimentally determined and modelled using a crushable foam model of ABAQUS. The packages are tested in free fall from a given height on a rigid floor. The deceleration of the packed product was recorded using a triaxial accelerometer. The numerical results obtained using the FE simulation with the homogenized model agree well with the experimental results. We have also shown that the contribution of the corrugated cardboard box to the shock response could not be neglected in the design of cushioning package.

This paper investigates the windage power losses generated by spur gears rotating in pure air by using a computational fluid dynamics (CFD) code. The three-dimensional simulations are at first validated comparing CFD predictions with the power losses measured in similar conditions from other investigations. The volumetric flow rate which is expelled by the teeth is then analysed, and a correlation which is based on a classical approach used in turbomachinery is finally proposed which makes it possible to estimate windage losses for spur gears. It was observed that this latter approach seems satisfying since the formulation of the volumetric flow rate which is employed in the model is appropriate to each gear.

The study of nonlinear dynamic behavior of laminate composed of steel and rubber layers also referred as “Shim”, used for vibro-acoustic insulation in brake system, is investigated. The simulation of the vibro-acoustic nonlinear behavior of Shim depending on frequency, taking into account the large deformations and various nonlinear hyper-viscoelastic laws of rubber are considered. This paper presents a solution to contribute in the identification of the best design of Shim in terms of damping vibration of brake systems, using analytical and numerical method. The choice of the best structure depends essentially on the nature of rubber, on the stacking sequence of materials, on their thickness, on the number of layers and on volume fraction of rubber. An analytical study, with the use of the transfer matrix method is presented. A model on the finite element software ANSYS is constructed. The results lead to conclusions about the best structure and design of Shim in term of vibro-acoustic insulation.