Publications

29/11/2023

MÉMOTVIT’ : L’apprentissage d’un champ lexical métier par les cartes : retours d’expériences

Authors : VIPREY, Fabien GEOFFROY, Régine TRUJILLO, Emmanuel CHEVIGNARD, Christine
Publisher :
MEMOTVIT', un jeu de cartes comportant des définitions, permettant à des apprenants d'acquérir des connaissances sur des champs lexicaux inhérents à une discipline, et ce par le biais d'une activité ludique, en équipe. C'est un jeu qui sollicite l'intelligence individuelle et collective ainsi que les sens. L'objectif est de fournir à l'apprenant la capacité à connaître un champ lexical par contextualisation en équipe, puis une décontextualisassions individuelle et enfin une recontextualisation en équipe. L'apprenant peut évaluer son niveau de connaissance en s'autoévaluant grâce à une évaluation formative seul ou en groupe, un questionnaire en ligne.
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29/11/2023

Development of an enhanced burr accumulation model during orthogonal cutting of nickel-based super alloy

Authors : LEGRAND, Côme FROMENTIN, GUILLAUME POULACHON, Gerard RANCIC, Mickael
Publisher : Springer Science and Business Media LLC
Burr size is a real issue in aeronautic for machining highly critical parts, such as broaching of turbine disks, it may affect the mechanical resistance of the part. However, the analysis and modelling of the burr formation and its accumulation is challenging due to the small concerned root area and the change of its shape after multiple cuts. In the state of the art, there is not much contribution on the burr mechanism during accumulation. To investigate this subject on nickel-based super alloy parts, an experiment with an in situ camera and LASER profilometer has been developed to follow the burr growth after multiple passes. Then, a phenomenological model of burr accumulation is formulated based on the description of a plastic hinge appearance during burr formations. It enables the modelling of burr height, root thickness and added material to the burr after each pass. Burr fracture occurrence is also discussed. This work proposes a new outlook on the burr formation mechanism and complete the models previously developed in the known literature.
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29/11/2023

In-Situ Pixel-wise Emissivity Measurement Using a Multispectral Infrared Camera

Authors : POISSENOT, Corentin MARCON, Bertrand ROSSI, Frederic FROMENTIN, GUILLAUME
Publisher : MDPI AG
In the thermography process, accurately determining emissivity is crucial to obtain precise temperature measurements as it enables the conversion of radiometric values to absolute temperatures. However, assessing emissivity is not a straightforward task as it depends on various other parameters. Traditional methods for measuring emissivity often involve costly materials and cannot be carried out simultaneously with infrared image acquisition. This article presents a method for obtaining pixel-wise emissivity using data from a multispectral infrared camera. Consequently, this method allows for direct emissivity measurement during infrared camera acquisition without the need for additional materials or experiments.
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28/11/2023

Towards the Real-Time Piloting of a Forging Process: Development of a Surrogate Model for a Multiple Blow Operation

Authors : URIBE, David DURAND, Camille BAUDOUIN, Cyrille KRUMPIPE, Pierre BIGOT, Régis
Publisher : Springer Nature Switzerland
Forging processes are defined by variables related to the workpiece, the tools, the machine, and the process itself, and these variables are called process variables. They have a direct impact on the quality of the finished product, so it is important to accurately define them at the very beginning of the process design. Nowadays, the design stage is supported by numerical simulations, however, these simulations are made under ideal process conditions and do not consider the dynamics of the forging machine or the variabilities that may occur in production (e.g., variabilities in the dimensions of the billet). This suggests that among the different process variables, those defined for piloting the process (such as the blows energies, for example) are fixed under nominal conditions and are not calibrated for each part produced. This study exploits a methodology in four steps to create a surrogate model and implement it into a machine-behavior model for real-time piloting of a forging operation with a screw press. This model supports the piloting of the operation, providing a value for the energy setpoint, according to the current state of process variables, these being the input of the model. The methodology is detailed for a multiple-blow cold upsetting of a copper billet.
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27/11/2023

From bio-sourced to bio-inspired cellular materials: A review on their mechanical behavior under dynamic loadings

Authors : LE BARBENCHON, Louise VIOT, Philippe
Publisher : Elsevier BV
Natural cellular materials can be used directly or as a constituent of bio-sourced composites for industrial applications involving dynamic loadings, usually for the purpose of absorbing mechanical energy. These biological materials can also be used as an inspiration to conceive more efficient heterogeneous structures for impact mitigation. In this review letter, we present two natural materials for which the properties have been studied dynamically: balsa wood and corkbased agglomerates. Both display an important strain-rate dependence but because of their different microstructure, this dependence is not the same. Consequently, a better understanding of the relationship between the hierarchical structure of natural cellular materials and their mechanical behavior, from quasi-static to dynamic, would be beneficial for the conception of new bio-inspired architected structures. We then focus on two types of bio-inspired architected structures: the functionally density graded cellular structures and the multi-layered architected structures. These two types of structures are gaining interest, but it appears that their dynamic behavior still lacks studying and understanding. More research linking the local strain mechanisms to their macroscopic mechanical behavior in quasistatic and dynamic would allow further architected structure optimization for mechanical energy absorption.
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27/11/2023

Remediation of multilayer soils contaminated by heavy chlorinated solvents using biopolymer-surfactant mixtures: Two-dimensional flow experiments and simulations

Authors : ALAMOOTI, Amir COLOMBANO, Stéfan GLABE, Zakari Abdullaziz LION, Fabien DAVARZANI, Dorian AHMADI-SÉNICHAULT, Azita
Publisher : Elsevier BV
To assess the efficiency of remediating dense non-aqueous phase liquids (DNAPLs), here heavy chlorinated solvents, through injection of xanthan solutions with or without surfactant (sodium dodecylbenzenesulfonate: SDBS), we conducted a comprehensive investigation involving rheological measurements, column (1D) and two-dimensional (2D) sandbox experiments, as well as numerical simulations on two-layers sand packs. Sand packs with grain sizes of 0.2–0.3 mm and 0.4–0.6 mm, chosen to represent the low and high permeable soil layers respectively, were selected to be representative of real polluted field. The rheological analysis of xanthan solutions showed that the addition of SDBS to the solution reduced its viscosity due to repulsive electrostatic forces and hydrophobic interactions between the molecules while preserving its shear-thinning behavior. Results of two-phase flow experiments depicted that adding SDBS to the polymer solution led to a reduced differential pressure along the soil and improvements of the DNAPL recovery factor of approximately 0.15 and 0.07 in 1D homogeneous and 2D layered systems, respectively. 2D experiments revealed that the displacement of DNAPL in multilayer zones was affected by permeability difference and density contrast in a heterogeneous soil. Simulation of multiphase flow in a multilayered system was performed by incorporating non-Newtonian properties and coupling the continuity equation with generalized Darcy's law. The results of modeling and experiments are very consistent. Numerical simulations showed that for an unconfined soil, the recovery of DNAPL by injection of xanthan solution can be reduced for more than 50%. In a large 2D experimental system, the combination of injecting xanthan with blocking the contaminated zone led to a promising remediation of DNAPL-contaminated layered zones, with a recovery of 0.87.
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27/11/2023

Evaluation of a decision-support tool for part orientation in EBM additive manufacturing

Authors : MECHEKOUR, El-Haddi VIGNAT, Frédéric GRANDVALLET, Christelle POURROY, Franck MARIN, Philippe René PAILHES, Jerome MBOW, Mouhamadou Mansour PRUDHOMME, Guy
Publisher :
The activity of part orientation is of crucial importance in terms of impact on the quality of parts in powder bed additive manufacturing. To support the decision-making of Computer Aided Manufacturing (CAM) operators, several knowledge and software models are proposed. Even if they seem to help operators in orientation process, their operational effectiveness still needs to be scientifically assessed. This paper proposes to evaluate the efficiency of a part orientation software in assisting CAM engineers in part orientation choice. The related software is based on the mathematization of action rules issued from a knowledge model. The knowledge involved to carry out the orientation activity is analyzed based on the users’ expertise. To do this, an empirical approach based on a case study is made with participants of different levels of skills. Several design scenarios including various part typologies to be oriented are submitted to engineers, before their manufacturing with Electron Beam Melting (EBM) technology. Two means of orientation are thus used for comparison, namely a manual orientation and a computer-aided orientation software. Based on the orientation results, an analysis of the software usage is undertaken. As an underlying result of our study, we have come up with an evaluation approach that can be reused in other contexts and with other software.
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27/11/2023

Machine learning for optimal flow control in an axial compressor

Authors : ELHAWARY, M. A. ROMANO, Francesco LOISEAU, Jean-Christophe DAZIN, Antoine
Publisher : Springer Science and Business Media LLC
Air jets for active flow control have proved effective in postponing the onset of stall phenomenon in axial compressors. In this paper, we use a combination of machine learning and genetic algorithm to explore the optimal parameters of air jets to control rotating stall in the axial compressor CME2. Three control parameters are investigated: the absolute injection angle, the number of injector pairs and the injection velocity. Given an experimental dataset, the influence of the air jet parameters on the surge margin improvement and power balance is modeled using two shallow neural networks. Parameters of the air jets are then optimized using a genetic algorithm for three rotational velocities. First, surge margin improvement and power balance are being maximized independently. Then, a bi-objective optimization problem is posed to explore the trade-off between the two competing objectives. Based on the Pareto front, results suggest that a globally optimal set of parameters is obtained for a velocity ratio (defined as the ratio of the injection velocity to the rotor tip speed) ranging from 1.1 to 1.6 and an injection angle attack. These outcomes point out a potential generalization of the control strategy applicable to other compressors.
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27/11/2023

Transition to turbulence in a heated non-Newtonian pipe flow

Authors : ROMANO, Francesco CHARLES, Antoine DOTTORI, François AMIR BAHRANI, S.
Publisher : AIP Publishing
A simplified mono-dimensional model for investigating the transition to turbulence in nonisothermal and non-Newtonian pipe flows is proposed. The flow stability is analyzed within the framework of such a model, showing that uniformly heating the pipe wall leads to an earlier transition to turbulence, while differentially heating the pipe wall produces a stabilizing effect. For power-law fluids, we also demonstrate that an increase in the power-law index, i.e., passing from shear-thinning to shear-thickening fluids, leads to a stabilization of the system.
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27/11/2023

Stability of generalized Kolmogorov flow in a channel

Authors : ROMANO, Francesco
Publisher : AIP Publishing
The Kolmogorov flow is a paradigmatic model flow used to investigate the transition from laminar to turbulent regimes in confined and, especially, in unbounded domains. It represents a solution of the forced Navier–Stokes equation, where the forcing term is sinusoidal. The resulting velocity profile is also sinusoidal with the same wavenumber of the forcing term. In this study, we generalize the Kolmogorov flow making use of a generic forcing term defined by a Fourier series that bridges the classical Kolmogorov flow to an arbitrary even-degree power-law profile. Thereafter, we perform a linear stability analysis on the power-law profiles for exponents, α=2, 4, 6, 8, and 10, and the corresponding generalized Kolmogorov flows, varying the truncation index K of the Fourier series. Several neutral stability curves are computed numerically for wall-bounded flows and the relevant critical conditions are compared in terms of critical Reynolds number, critical wavelength, and eigenspectrum at criticality. The most dangerous perturbations are thoroughly characterized, and we identify three qualitatively different most dangerous modes, depending on α, K, the Reynolds number, and the perturbation wavelength.
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